Browsing by Author "Strauss, Steven H., advisor"
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Item Open Access Chloro-, aryl-, and perfluoroalkylfullerenes(Colorado State University. Libraries, 2009) Kuvychko, Igor V., author; Strauss, Steven H., advisor; Prieto, Amy L. (Amy Lucia), committee member; Hochheimer, Hans D., committee member; Rappé, Anthony K., 1952-, committee member; Elliott, Cecil Michael, committee memberThe preparation, properties, stability, and handling of three classes of fullerene derivatives, chloro-, aryl-, and perfluoroalkylfullerenes, were studied in detail, in some cases for the first time. The same general methodology was used throughout this work: i) analytical methodology was developed and optimized using internal standards of known composition and purity; ii) the preparation of new compounds was studied by mapping the space of different reaction conditions using the newly developed analytical methods; iii) the efficient synthetic methods for the preparation of individual pure compounds were developed based on the mapping; iv) the pure compounds were characterized and their stability, or lack thereof, was studied. The first detailed study of fullerene chlorination led to isolation and characterization of several new chlorofullerenes: o-C60Cl2; p-C60Cl2; C60Cl4; C60Cl10; C70Cl6; and C70Cl8. It was discovered that chlorofullerenes are generally photosensitive in solution, both in the presence and absence of air and moisture. Effective methods for handling chlorofullerenes were developed (including a specialized crystallization technique). The experimental findings and theoretical calculations revealed the fundamental patterns governing multiple additions to fullerene cages. The efficient preparation of aryl- and perfluoroalkylfullerenes from chlorofullerene synthons was developed, leading to high yields of aryl- and mixed perfluoroethyl/hydrofullerenes (i.e., C60(C2F5)5H and C60(C2F5)3H). The first example of an organometallic complex of a perfluoroalkylfullerene was prepared using C60(C2F5)5H as a synthon. The direct addition of thermally-generated CF3 radicals to fullerenes was also studied. A specialized reactor was designed and built in order to validate mechanistic hypotheses. Good agreement between the experimental observations and predictions based on the hypotheses was observed. It led to the development of a new approach to efficient synthesis of C60(CF3)n with low values of n, including an unprecedented selective synthesis of C60(CF3)2 from unpurified fullerene extract.Item Open Access Direct fluorination of K2B12H12 and synthesis and characterization of metal salts of B12F122-(Colorado State University. Libraries, 2011) Peryshkov, Dmitry V., author; Strauss, Steven H., advisor; Rappe, Anthony K., committee member; Elliott, C. Michael, committee member; Bernstein, Elliot R., committee member; Ridley, John R., committee memberA significantly improved large-scale (10 g) perfluorination of K2B12H12 is described. The advantages of the new procedure are: (i) a ten-fold increase in the scale of the reaction with no sacrifice in yield or product purity; (ii) acetonitrile is used as the solvent instead of anhydrous HF; and (iii) a glass reaction vessel is used instead of a Monel reactor. DFT calculations and experimental data are reported that suggest that the absence of acidity significantly increased the rate and improved the efficiency of the reaction. Number of salts of Li+; Na+; K+; Rb+; Cs+; NH4+, Ag+; Mg2+; Ca2+; Ba2+; Co2+; Ni2+; and Zn2+ and the B12F122- anion were prepared and 24 crystal structures (some compounds were prepared by others) were determined. The thermal stabilities of the Mm(L)nB12F12 salts were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was found that Cs2B12F12 is stable up to 600 °C under an inert atmosphere, which is the highest temperature among weakly coordinating fluoroanions. The compounds K2B12F12, Rb2B12F12, Cs2B12F12, and Ag2B12F12 were prepared as ligand-free solids. It was found that the K2(H2O)0,2,4B12F12 system of compounds can undergo rapid interconversion among the three crystalline phases, two of them reversibly in presence of water vapor. The reversible interconversion was found to be a reconstructive (i.e., topotactic) solid-state reaction and, when carried out very slowly, a single-crystal-to-single-crystal transformation. The exchange of H2O(g) with either D2O or H218O in crystalline K2(D2O)2B12F12 or K2(H218O)2B12F12 at 25 °C was also rapid. The new concept of latent porosity, as ligands rapidly enter a lattice and displace some of the weak and non-directional M•••F(B) bonds in salts of the large, highly-symmetric, superweak anion B12F122-, is presented and discussed.Item Open Access Fluorinated materials synthesis and characterization for energy storage and energy conversion applications(Colorado State University. Libraries, 2015) Bukovsky, Eric V., author; Strauss, Steven H., advisor; Ackerson, Christopher, committee member; Crans, Debbie, committee member; Barisas, B. George, committee member; Sutton, Sally, committee memberThe synthesis and characterization of multiple fluorinated, p-block, cage, and organic compounds will be presented. The research effort is split up in to main topics, (i) fluorinated superweak anions based on B12 cages, and (ii) perfluoroalkylation of polycyclic aromatic hydrocarbon (PAH) and fullerene compounds. In the first three chapters, superweak anion research is presented; a new purification method for the synthetic intermediate K2B12F12, synthesis and thermal and physical characterization of highly purified (H3O)2B12F12·nH2O, Li2B12F12 and Na2B12F12 (synthesized from K2B12F12), and an HF-free, improved synthesis method and characterization of KB12F11NH3. Furthermore, the unanticipated, rapid fluorination of KB12H11NH3 in the presence of HF, contrary to, previously observed, slowed fluorination of K2B12H12 in the presence of HF, will also be described. Single crystal X-ray structures of three new isomers of C60(CF3)10 are discussed, and one putative isomer of C60(CF3)10 is confirmed along with comparisons of their crystal packing properties compared to 1,9-C60(cyclo-CF2(2-C6F4)), and industry-standard fullerene acceptor phenyl-C61-butyric acid methyl ester (PCBM). Discussion of how the structural and electrochemical data of the new C60(CF3)10 isomers and 1,9-C60(cyclo-CF2(2-C6F4)) agree with currently accepted literature will also be discussed. A new metal reactor design for the radical reactions of CF3I and polycyclic aromatic hydrocarbons (PAH) and fullerenes, and initial results will be discussed and compared to previous reaction methods. Single crystal X-ray structures of four separate compounds believed to be "trapped intermediates" formed from the radical substitution reaction isolated from radical reactions with CF3I using different PAHs and different reactions conditions will be discussed as well as the implications these trapped intermediates have on the proposed mechanism of CF3• radical substitution reactions. Crystal packing and nearest molecule analysis of five PAH(CF3)n will be compared to a single crystal X-ray structure of triphenylene with a C4F4 substitution. Insights into the structural effects of CF3 substitutions compared to the flat C4F4 substitutions, and, how those effects would translate into electronic communication in the solid state will be discussed. Finally, wet milling of metallurgical grade silicon in an attritor mill, under anaerobic and aerobic conditions with and without surface passivating additives to study the affects oxygen and additives can have on milled particle properties such as, crystallinity by powder X-ray diffraction, surface bonds by X-ray photoelectronspectroscopy, dynamic light scattering particle size, N2 gas uptake BET surface area and reactivity towards oxygen will be discussed. Under anaerobic conditions silicon was found to form Si–C bonds in the presence of dry- air-free heptane. Additionally, the extensive effect oxygen has on the comminution of silicon and the surprising result that, even in aerobic conditions, formation of Si–C bonds is observed. All of the research described in this dissertation has applications in one or multiple energy storage or energy conversion devices. The superweak anion salts as electrolyte salts in battery or fuel cell, C60(CF3)10 and 1,9-C60(cyclo-CF2(2-C6F4)), as electron acceptor materials in organic photovoltaic devices, and multiple PAH(CF3)n compounds as OLED active layer materials.Item Open Access Fluorine-containing fullerenes and endometallofullerenes: synthesis, structure, and spectroscopic characterization(Colorado State University. Libraries, 2010) Shustova, Natalia Borisovna, author; Strauss, Steven H., advisor; Anderson, Oren P., committee member; Szamel, Grzegorz, committee member; Elliott, Cecil Michael, committee member; Roess, Deborah A., committee memberMany new members of a relatively new class of exohedral fullerene derivatives with fluorine-containing electron-withdrawing groups have been prepared and studied by spectroscopic methods and X-ray crystallography. The fluorination and/or perfluoroalkylation reactions were performed with C60, C70, the higher hollow fullerenes C60+m (m = 14, 16, 18, 20, and 22), the endohedral metallofullerene Sc3N@C80-Ih(7), and the azafullerene dimer (C59N)2. Several efficient synthetic methods have been developed for perfluoroalkylation, which involved high-temperature reactions with AgCF3CO2 and with thermally or photochemically activated reactions with RFI reagents (RF = CF3, C2F5, n-C3F7, i-C3F7, n-C4F9, and n-C6F13). Structural studies of the C60(RF)n and C70(RF)n products demonstrated that variation of the size and structure of the RF radical led to the formation of derivatives with unprecedented addition patterns and hence unprecedented properties. Many of these derivatives were shown to have superior electron-accepting properties. Trifluoromethylation of a sample of insoluble hollow higher fullerenes resulted in the structural characterization of several new dodecakis(trifluoromethyl) fullerene compounds, and this led to the first experimental observation of fullerenes C74-D3h and C78-D3h(5). In the case of trifluoromethylation of (C59N)2, a strong effect of the heteroatom on the addition patterns of the products was discovered. The first X-ray crystal structure of a single regioisomer of C59N(CF3)5, as well as spectroscopic studies of C59N(CF3)7,9,11, revealed unexpected addition patterns which resemble that of Cs-C60X6 derivatives. The isolation and characterization of seventeen Sc3N@(C80-Ih)(CF3)n (even n = 2-16) compounds, including the X-ray structures of Sc3N@(C80-Ih(7))(CF3)10, Sc3N@(C80-Ih(7))(CF3)12, Sc3N@(C80-Ih(7))(CF3)14, and Sc3N@(C80-Ih(7))(CF3)16, have demonstrated for the first time a strong mutual effect of (i) the presence of the Sc3N cluster on the addition pattern and (ii) the addition pattern on the position of and structure of the Sc3N cluster.Item Open Access Fluoroalkyl and fluoroaryl fullerenes, polycyclic aromatic hydrocarbons, and copper(I) complexes: synthesis, structure, electrochemical, photophysical, and device properties(Colorado State University. Libraries, 2020) Reeves, Brian J., author; Strauss, Steven H., advisor; Shores, Matthew P., committee member; Rappé, Anthony K., committee member; McNally, Andrew, committee member; Ridley, John, committee memberIn many fields of research, ranging from materials chemistry to medicinal chemistry, understanding the structural, electrochemical, and photophysical properties of materials is essential to establishing trends and predicting usefulness and future performance. This work has focused on the impact of strongly electron withdrawing perfluoroaryl and perfluoroalkyl substituents on the properties of fullerenes, polycyclic aromatic hydrocarbons (PAHs), hetero-PAHs, and copper(I) complexes with the goal of establishing and understanding the fundamental reasons for any observed trends. In Chapter 1, the first successful example of vacuum-deposited organic photovoltaic cells (OPVs) based on a fullerene derivative and a small-molecule donor is reported. A series of thermally robust fluorous fullerene acceptors with experimental gas-phase electron affinities ranging from 2.8 to 3.3 eV are paired with new dicyanovinyl thiophene-based molecular donors to enable direct comparison of their performance in planar and bulk heterojunction architectures in cells fabricated by vacuum deposition. Unprecedented insights into the role of the acceptor intrinsic molecular and electronic structures are obtained, which are not obscured by solvent and additive effects as in the typical solution-processed fullerene-based OPVs. Additionally, the fullerene derivative, C60CF2, was utilized in vacuum-deposited organic field effect transistors (OFETs), and it was shown to have superior device lifetime compared to C60 based OFETs. In Chapter 2, a new synthesis of 9,10-bis(perfluorobenzyl)anthracene, a promising blue organic light emitting diode (OLED) material is reported. The yield was improved from 7% to 17%, while the separations conditions were improved to only require one stage of HPLC. In Chapters 3 and 4, the trifluoromethylation of two hetero-PAHs, phenanthroline and phenanthridine, is discussed. The structure, solid-state packing, and electronic properties of the products are examined. Previously unknown structure-property relationships were established between the electronic properties and the position of CF3 groups. Additionally, the synthesis and excited-state dynamics for a series of homoleptic copper(I) phenanthroline complexes with 2, 3, and 4 trifluoromethyl groups are reported. Surprisingly, the observed time-resolved dynamics and emission trend is that addition of trifluoromethyl groups past two decreases the excited state lifetime and increases excited-state distortion.Item Open Access Modifying electronic and solid-state properties of fullerenes, polycyclic aromatic hydrocarbons, and perylene diimides(Colorado State University. Libraries, 2015) Clikeman, Tyler T., author; Strauss, Steven H., advisor; Rumbles, Garry, advisor; Shores, Matt P., committee member; Chen, Eugene Y.-X., committee member; Bailey, Travis, committee member; Sites, Jim, committee memberThe growing world energy demand necessitates the development of novel, cheap, and efficient energy sources and low energy consumption electronics devices. Organic photovoltaics, transistors, and light-emitting diodes are actively being developed as replacements for traditional energy sources and electronic devices. Strong electron acceptors are required to increase the efficiency and air stability for many of these applications. Studying how the incremental introduction of strong electron-accepting moieties onto electron-accepting substrates can affect performance is essential for systematically developing new devices. Furthermore, synthetic methodologies and characterization of these molecules are essential before incorporation into real world applications. This dissertation focuses on synthesizing families of strong electron acceptors via modification with strong perfluoroalkyl or cyano electron-withdrawing groups for fundamental studies in the development of advanced electronics. The first chapter focuses on the synthesis and characterization of new trifluoromethylfullerene derivatives. Synthetic methods for adding CF3 groups to C60, C70, and M3N@C80 are discussed and new CF3 addition patterns are revealed by single crystal XRD. Then the addition of electrophiles, nucleophiles, and cycloadducts to these trifluoromethylfullerene derivatives are discussed. Adding single nucleophiles and electrophiles to the cages along with collaborative DFT studies show which cage carbon atoms are most susceptible towards additional attack. The variations in electron accepting behavior were studied by adding a combination of electron-withdrawing and electron-donating groups at these specific locations on the fullerene cage. The studies revealed that these groups can modify electronic behaviors incrementally and somewhat unexpectedly by disrupting the fullerene π system. Understanding where and why new groups add to the fullerene cages and how they affect electronic behaviors could be used as the foundation for synthesizing new fullerene molecules to be used in advanced electronic devices. The second chapter concentrates on substituting electron-withdrawing fluorinated groups onto polycyclic aromatic hydrocarbon substrates. A family of poly(trifluoromethyl)azulene derivatives was synthesized and characterized for the first time. Trifluoromethylation of azulene systematically increases the electron-withdrawing strength and affects solid-state packing motifs. The molecular structures and solid-state packing of four other families of fluorine-modified polycyclic aromatic hydrocarbon substrates, corannulene, phenazine, triphenylene, and anthracene, were studied using single crystal XRD. Not only did XRD reveal previously unknown substitution patterns, but it was able to show where close π- π interactions existed within the packing structure, which could be extrapolated to solid-state charge transport in future applications. The third chapter focuses on developing a new series of perylene diimide acceptors and their use in organic photovoltaic active layers. Perylene diimides with previously unknown substitution patterns were synthesized with CF3 and CN groups and then isolated to isomeric purity using HPLC. Substituting with these strong electron-withdrawing groups at specific positions modified absorption, emission, solid-state packing, and solution- and gas-phase electron-accepting strength. These properties were compared within the entire series and solution reduction potentials were compared with a comprehensive list of literature reported perylene diimide acceptors. It was found that these properties were dependent on position and were not constant for each substituent. The series of poly(trifluoromethyl)perylene diimides were then blended with polymer donors and tested in photovoltaic active layer films. The systematic tuning of electron-withdrawing strength was used as a handle for fundamental studies on how increased electron affinity and fluorination affect charge transfer in the solid-state. All of the perylene diimides were able to accept charge from the polymer donors, but increasing the electron- withdrawing strength by introducing more fluorine atoms did not improve the charge separation yield.Item Open Access New approaches to fluoromodifications of electron acceptor molecules for organic photovoltaics(Colorado State University. Libraries, 2021) Brook, Colin P., author; Strauss, Steven H., advisor; Prieto, Amy L., committee member; Kennan, Alan J., committee member; Gelfand, Martin P., committee memberThe overall goal of this work is to advance fundamental science and applications of organic electron acceptors based on fluorinated fullerenes and polycyclic aromatic hydrocarbons. The synthetic part of the dissertation focused on the development of new synthetic approaches towards the fluoromodification of large conjugated organic molecules and on the improvements of existing methods for the preparation of high-performing fullerene-based n-type semiconductors. Chapter 1 describes development and application of a new configuration of the gradient-temperature gas-solid reactor for the efficient and high-yielding trifluoromethylation of fullerenes. Significant improvements were achieved in the yields and selectivity of bis-trifluoromethylated C60 and C70 fullerenes: 2-fold and 10-fold yield increase compared to prior state of the art, respectively. An approach to maintain a constant reactive gas pressure in the reactor has been introduced by creating a liquid-gas reservoir of CF3I by submerging the reservoir in one of several low-temperature slush baths available that resulted in improvements in both yields and selectivity for trifluoromethylfullerenes, while also solving a problem of previously unproductive use of the gaseous reagent. Chapter 2 presents the author's work in partnership with the National Renewable Energy Lab (NREL) aimed at investigation of the prominent stabilizing effect of perfluoroalkylated fullerenes on the rate of photobleaching of common high-performance donor-polymers used in OPV devices, compared to the pure polymer films and blends with prototypical non-fluorinated fullerene, PC60BM. It is demonstrated that rationalizing complex photobleaching behaviour ultimately required consideration of the electron affinity of the fullerene as well as the relative miscibility of the polymer–fullerene blend. The ability of the bis-trifluoromethylfullerene and Fauxhawk fullerene to stabilize certain donor materials against photodegradation, to blend well with fluorinated (and even certain non-fluorinated) polymers, and to quench excited states efficiently was thoroughly studied and correlated with structure-property relationships amongst several polymer donor and fullerene acceptor combinations. Chapter 3 describes a new approach to the direct fluoromodification of polycyclic aromatic hydrocarbons based on replacing commonly used perfluoroalkyl groups (CnF2n+1, or RF) with perfluorobenzyl groups (C6F5CF2, or BnF). For the first time, solution-phase direct perfluorobenzylation of an electron-rich perylene (PERY) and electron-poor perylene diimide (PDI), has been achieved. Five new bay- and peri-substituted compounds of perylene, PERY-(BnF)n, where n = 1, 2 and 3; and three new bay-substituted compounds of perylene diimide, PDI-(BnF)n, where n = 1, 2; were synthesized and fully characterized, revealing that electron withdrawing BnF group is comparable to RF in increasing acceptor strength of new compounds. Chapter 4 deals with a new type of annulative pi-extension (APEX) reaction discovered in this work that occurs via reductive dehydrofluorination/aromatization reactions involving perfluorobenzylated PDI compounds, that afforded fluorinated benzoperylene and coronene-based derivatives with prodigious electron acceptor properties. Another type of annulation leading to the transition-metal free formation of new compounds with all-carbon seven-membered rings across the bay regions of PDIs, consequently forming as rare examples of a newly-recognized fundamental type of conformational isomers, named akamptisomers, is also reported here for the first time. Studies of the likely reaction pathways in both types of reactions and effects of varying reaction parameters on the preferred product formation are presented. Single crystal crystallographic studies of many of the new compounds prepared in this work provide rich and unique data for in-depth analysis of the solid-state packing motifs and influences of the type and position of fluorinated functional groups on the intermolecular interactions, and ultimately, charge transport in these new organic n-type semiconductor materials.Item Open Access Preparation, regioselective chemistry, and electronic properties of perfluoroalkylfullerenes(Colorado State University. Libraries, 2013) Whitaker, James B., author; Strauss, Steven H., advisor; Chen, Eugene, committee member; Finke, Rick, committee member; Williams, Bob, committee member; Ridley, John, committee memberA systematic study of how various reaction parameters affect the product distribution of gas-solid reactions was carried out in a new reactor of local design. These reactions involve the trifluoromethylation of C60, C70, and the endohedral metallofullerenes Sc3N@C80 and Y3N@C80; and in particular, the reactions were optimized to favor C60(CF3)2 and C60(CF3)4. A new solution phase homogeneous perfluoroalkylation method was used to prepare a series of 1,7-C60(RF)2 compounds with different RF chain lengths and branching patterns. A range of analytical methods including 19F NMR and UV-vis spectroscopy, APCI mass spectrometry, and X-ray crystallography were used to structurally characterize the compounds. Cyclic voltammetry, DFT E(LUMO) calculations, and gas phase electron affinity (EA) measurements were used to determine the substituent effect of the RF groups. The results conclusively showed that the solution phase E1/2, calculated E(LUMO), and EA values-- that are typically assumed to be correlated for a series of electron acceptors-- are not always correlated. Several highly efficient and selective methods were developed for the further functionalization of selected trifluoromethyl fullerenes (TMFs). These new functionalized TMFs were structurally characterized using the aforementioned analytical techniques and the X-ray crystal structures of five new derivatized TMFs were determined. Analysis of the how these newly derivatized TMFs pack in a crystalline solid revealed fullerene density values that were in general twice that of reported fullerenes that pack in the same motifs. These derivatized TMFs also exhibited extended networks of short C···C distances between fullerene cages of adjacent molecules that has been correlated to increased free charge carrier motilities in organic photovoltaic device active layers. The solution phase E1/2 values of the most commonly used fullerene derivatives in OPV devices were measured under carefully controlled conditions and revealed that poor reporting of electrochemical conditions, mistakes interpreting electrochemical data, and fullerene impurities have combined to cause significant confusion about the reported electrochemical values in the literature. A preliminary study of 32 OPV devices fabricated with active layers containing perfluoroalkylfullerenes (PFAFs) indicated that (i) PFAFs can function as suitable electron acceptors in OPVs, and (ii) that a more detailed study examining the complex electronic interplay between the fullerene electron acceptor and polymer donor is warranted.Item Open Access Selective two-electron reductive defluorination of 1-Me-CB(11)F(11-) and related anions: synthesis and characterization of salts of 1-Me-12-R-CB(11)F(10-) and related anions(Colorado State University. Libraries, 2008) Kobayashi, Yoshihiro, author; Strauss, Steven H., advisorIn this dissertation, a method to selectively defluorinate and functionalize the antipodal B-F bond in 1-R-CB11F11-anion is described. The defluorination reaction mechanism using sodium naphthalenide to form an intermediate anion was investigated by 19F{ 11B} NMR, cyclic voltammetry, and computational analysis. The stoichiometric amount of sodium naphthalenide to reduce 1-Me-CB11F11 - was determined to be two. 19F{11B} NMR of the intermediate did not show a peak due to the antipodal fluorine atom, which suggested that the B-F bond is broken. Cyclic voltammetry of 1-Me-CB 11F11- showed a reversible one-electron reduction. In presence of excess Na+, the reduction occurred as an irreversible two-electron process, but at the same potential as the one-electron process. The addition of excess 18-crown-6 restored the reversible one-electron process. This suggested that Na+ is probably incorporated in the structure of the intermediate. Based on these results, two structures were proposed, one with B···F···Na+ linkage the other with B···Na+···F - linkage at the antipodal position. The intermediate did not show electron-exchange between the intermediate and the starting material, 1-Me-CB 11F11-. This suggested that the structure with B···F···Na+ is unlikely. Computational analysis of the proposed structures predicted that the latter structure is 55 kJ/mol more stable than the former. From these results, the structure of the intermediate was suggested to be (1-Me-CB 11F11···Na+···F -)2-. Using various electrophiles, several derivatives of 1-Me-12-R-CB 11F10-. For example, when methyl iodide was added to the intermediate solution, the major product was 1,12-Me2-CB 11F10-. An isomer, 1-Me-7-X-CB11F 10- was formed as one of the byproducts, however, the isomeric ratio of the 12-isomer and the 7-isomer was 9:1. X-ray crystal structures of four new compounds NMe4(1,12-Me 2-CB11F10), Cs(1-Me-12-I-CB11 F10), Cs(1-Me-12-SiPh3-CB11F10), and Ag2(1-Me-12-SiPh3-CB11F 10)2·C6H6 were obtained. The characteristics of each structure are described. One of them, Ag2(1-Me-12-SiPh 3-CB11F10)2·C6H 6, contained two Ag+ with different coordination spheres. One of them was the first example of tetrahediral Ag(arene)4 +. In order to investigate the effect of substitution on the B12 vertex of 1-Me-CB11F11- on the coordinating and ion-pairing abilities of the anions, DFT calculations were performed with 1-Me-CB11F11-, 1,12-Me2-CB 11F10-, and 1-Me-12-H-CB11F 10-. The calculations predicted that both 1,12-Me 2-CB11F10- and 1-Me-12-H-CB 11F10- had slightly less ion-pairing ability than 1-Me-CB11F11-. Especially, significant change was observed on the B 12-X direction on the ion-pairing ability. The solution conductivities of N(n-Bu)4(1-Me-CB 11F11) and N(n-Bu)4(1,12-Me 2-CB11F10) also showed that N(n-Bu) 4(1,12-Me2-CB11F10) is 16% more conductive than N(n-Bu)4(1-Me-CB11F11). The DFT-predicted relative energies of the 12-, 7-, and 2-isomers of Fe(Cp)(CO) 2(1-Me-CB11F11), Fe(Cp)(CO)2(1,12-Me 2-CB11F10), and Fe(Cp)(CO)2(1-Me-12-H-CB 11F10) were also calculated. For Fe(Cp)(CO)2(1-Me-CB 11F10), the 12-isomer was predicted to be the most stable. This suggests that the B12-vertex is the most strongly coordinating. For Fe(Cp)(CO) 2(1,12-Me2CB11F10), the strongest coordinating site is on the B7-F7 direction, however, the difference between the 12- and 7-isomers was only 1.8 kJ/mol. For Fe(Cp)(CO)2(1-Me-12-H-CB 11F10), 12-isomer was the most stable, and 7- and 2- isomers were predicted to have much higher energies than the 12-isomer.Item Open Access Static and dynamic study of metal salt hydrates of weakly-coordinating fluoroanions by vibrational spectroscopy, gravimetry, and an analysis of previously published x-ray structures(Colorado State University. Libraries, 2021) Lacroix, Matthew R., author; Strauss, Steven H., advisor; Chen, Eugene, committee member; Bandar, Jeff, committee member; Ridley, John, committee memberEighteen metal salt hydrates (Li(H2O)4(Al(OC(CF3)3)4), Li(H2O)(B(3,5-C6H3(CF3)2)4), Li(H2O)n(Ga(C2F5)4), Li(H2O)(PF6), Na(H2O)(PF6), Li2(H2O)4(B12F12), Na2(H2O)2(B12F12), K2(H2O)2(B12F12), Rb2(H2O)2(B12F12), Cs2(H2O)(B12F12), Mg(H2O)6(B12F12), Ca(H2O)n(B12F12), Sr(H2O)n(B12F12), Ba(H2O)n(B12F12), Co(H2O)6(B12F12), Ni(H2O)6(B12F12), Zn(H2O)6(B12F12), and Li2(H2O)2(TiF6)) containing weakly coordinating anions were analyzed using room temperature ATR-FTIR spectroscopy. The goal was to investigate the relative strengths of water–anion hydrogen bonds in the solid-state. In all but one case, these hydrogen bonds take the form of O–H···F hydrogen bonds. The one exception is in the salt Li2(H2O)4(B12F12) where there are both O–H···F and O–H···O hydrogen bonds present. Based on the magnitude of the redshift of the ν(OH) band(s) a qualitative scale for the comparison of the relative hydrogen bond strength is constructed. Included in this scale are additional metal salt hydrates taken from the literature. This spectroscopic study has produced some of the only room temperature spectra for water participating in hydrogen bonding in the solid-state where the νasym(OH) and νsym(OH) bands are individually resolvable. The weak nature of the O–H···F hydrogen bonds allows for resolution of ν(OH) bands only 5 cm−1 apart in some cases. The two metal salt hydrates (Li(H2O)4(Al(OC(CF3)3)4) and Li(H2O)(B(3,5-C6H3(CF3)2)4) are shown to possess the weakest O–H···F hydrogen bonds observed in the solid state at room temperature. The salt Li2(H2O)4(B12F12) contains a cyclic (H2O)4 water cluster, also known as the R4 cluster, is presented, and discussed in the context of the FTIR spectrum of water clusters. Due to the nature of the weak O–H···F hydrogen bonding between the cluster and the surrounding anions the E and B fundamental vibrations for the cluster were able to be determined. The peak-to-peak separation, and relative intensities of these two bands are consistent with computational results from the literature. This is the first time that the R4 water cluster has been successfully studied via FTIR spectroscopy without the presence of other clusters leading to ambiguity in the results. Finally, direct observation of the effect of cation acidity on the relative strength of water–anion hydrogen bonding has been directly observed for the first time in the metal hexahydrate salts M(H2O)6(B12F12) (M = Mg, Co, Ni, Zn). These results, along with the correlation curves constructed in this work, show that it is not possible to assign relative hydrogen bond strength based on O–H···X bond length, nor is it possible to accurately approximate O–H···X bond length based on degree of ν(OH) redshift. Instead, it is shown that the relative basicity of the anion is the primary factor governing the relative hydrogen bond strength, and thus the degree of redshifting experienced by the ν(OH) band(s). The cation acidity also is shown to have a lesser, but observable, effect on the relative strength of O–H···X hydrogen bond. In addition to broadening our fundamental understanding of hydrogen bonding in the solid state, this work also shows that FTIR spectroscopy can be a useful tool for rapidly assigning relative basicity of new weakly coordinating anions without need the for complex protonation experiments.Item Open Access Strong fullerene and polycyclic aromatic hydrocarbon electron acceptors with perfluorinated substituents(Colorado State University. Libraries, 2015) San, Long K., author; Strauss, Steven H., advisor; Henry, Charles, committee member; Borch, Thomas, committee member; Szamel, Grzegorz, committee member; Wang, Qiang, committee memberThe world energy consumption is increasing at an alarming rate and only 10% comes from renewable energy resources. Harnessing the potential energy provided by the sun would provide enough energy to meet the world energy demands and more. One method to improve the collection of solar power is to provide materials that are lightweight, flexible, robust, and low manufacturing costs. The focus of this dissertation include the molecular design of novel materials to be used as organic semiconductors in a variety of applications such as organic photovoltaic and organic light emitting diodes. One very important aspect of these organic electronics is the electron acceptors employed in such devices. The need for strong electron acceptors and higher stabilities under thermal and oxidative stress were investigated by the perfluoroalkylation and perfluorobenzylation of fullerenes and polycyclic aromatic hydrocarbons. The first chapter of this dissertation demonstrates the novel fullerene derivative (nicknamed faux hawk) that possesses physicochemical properties suitable for use in organic photovoltaics. In fact, an organic photovoltaic figure of merit (ϕΣμ, yield of free charge carriers x sum of the charge carrier mobilities) determined from time resolved microwave conductivity measurements showed that faux hawk is comparable to that of the most studied fullerene electron acceptor, PCBM. Other properties are compared between faux hawk and PCBM. Mechanistic insight revealed, for the first time in fullerene chemistry, the formation of a carbon–carbon bond via a carbanion from the fullerene cage. The second chapter of this dissertation investigates novel polycyclic aromatic hydrocarbons containing fluorine withdrawing functional groups via perfluoroalkylation and, for the first time, perfluorobenzylation. These fluoromodifications have profound influences on the physicochemical and electronic properties that are all important for designing new electron acceptors. For example, the perfluorobenzylation greatly affects the π‐π intermolecular interactions and is more electron withdrawing than the trifluoromethyl group. Often times a bulky functional group is desired to promote certain properties (i.e., fluorescence). Several analytical methodologies including ¹⁹F and ¹H NMR spectroscopy, absorption and emission spectroscopy, mass spectrometry, cyclic voltammetry, gas-phase electron affinity, low-temperature photoelectron spectroscopy, X-ray diffraction, and DFT calculations are used to characterize the compounds discussed. These fundamental studies allow for future molecular engineering and design of even stronger electron acceptors. At the same time, the organic semiconductor library is expanding for use in optoelectronics.Item Open Access Synthesis and characterization of fluorine-containing C60 derivatives and their charge transfer photophysics in organic photovoltaics(Colorado State University. Libraries, 2013) Larson, Bryon W., author; Strauss, Steven H., advisor; Rumbles, Garry, advisor; Rappé, Anthony, committee member; Bartels, Randy, committee member; Chen, Eugene, committee member; Robinson, Raymond S., committee memberTransformative advances in the science of new materials and technological solutions for energy conversion and storage require focused efforts from scientists across different disciplines. One of the major frontiers for modern chemistry is the molecular design of advanced materials from earth-abundant elements with finely tuned chemical, photophysical, and electronic properties. In this work, several highly efficient and, in some cases, highly regioselective synthetic methodologies have been developed for the first time that resulted in a wide array of versatile fullerene-based organic electron acceptors with highly tunable electronic properties. The classes of these newly synthesized and characterized materials include mono-perfluorocarbocyclic C60 derivatives, highly functionalizable ω-X-perfluoroalkylfullerenes (X = SF5, Br, I, COOEt), twenty one new isomers of deca-trifluoromethyl[60]fullerenes, and several new isomers of octa- and hexa-trifluoromethyl[60]fullerenes. Improved synthetic and separation techniques yielding up to multi-gram amounts of difluoromethylene[60]fulleroid and several other classes of technologically important perfluoroalkylfullerenes have also been developed, which enabled several organic photovoltaic-relevant studies using state-of-the art facilities at the National Renewable Energy Laboratory. This included the first experimental determination of an optimal driving force for the relative yield of free carrier generation in a family of polyfluorene polymers by using a series of trifluoromethylfullerene acceptors with a large range of electron affinities synthesized by the author. In another study, a judiciously selected series of acceptors was applied for a time-resolved microwave conductivity (TRMC) study that provided the first compelling experimental evidence that the yield for uncorrelated free charge generation in organic photovoltaic (OPV) device-relevant blends of donor:acceptor active layers is a function of carrier mobility. Finally, a new fullerene acceptor rivaling one of the champion fullerene derivatives, phenyl-C61-butyric acid methyl ester (PCBM), in OPV performance was studied by TRMC and in OPV devices.Item Open Access Synthesis and evaluation of fluorous polycyclic aromatic hydrocarbon derivatives for organic electronics(Colorado State University. Libraries, 2019) Rippy, Kerry C., author; Strauss, Steven H., advisor; Prieto, Amy L., committee member; Sites, James R., committee member; Szamel, Grzegorz, committee memberAdvances in the performance of electron acceptor materials for organic electronics critically depend on the efficiency of synthetic routes for new materials and fundamental understanding of the correlation between molecular structure and electronic and solid-state properties. The research presented here endeavors to address both of these needs, by developing original methods for synthesis of new organic electron acceptor materials, and by characterizing relevant properties of the resulting materials. In total, synthesis and analysis of more than 60 new molecules is presented in this work. These molecules are derivatives of polycyclic aromatic hydrocarbons (PAHs) and hetero-PAHs functionalized with fluorous moieties, synthesized via development of substrate-specific efficient, single-step direct-substitution methods. Investigation of solid-state and electronic properties focused upon effects of structural motifs including (i) the type, number, and position of electron withdrawing fluorous substituents (ii) the size and shape of aromatic π systems, and (iii) presence of hetero atoms within the aromatic core. The first chapter of this work details the development and optimization of a gas-phase radical reaction between the perfluoroalkyl diiodide 1,4-C4F8I2 and the PAH triphenylene (TRPH). The perfluoroalkyl diiodide, with two C–I bonds, one at either end, has the unique ability to bind to vicinal C atoms, forming a 6-membered ring. A family of TRPH derivatives functionalized with such rings was synthesized, and the reaction was optimized. Additionally, reductive partial defluorination of the perfluoroalkyl ring was achieved, leading to aromatization of the fluorous substituent (RD/A). The extension of the π-system, as well as the effect of fluorine atoms bound directly to the aromatic system, was examined with respect to solid-state packing and electronic levels. In Chapter 2, results of screening of 13 new PAH and n-hetero PAH substrates with respect to their reactivity towards 1,4-C4F8I2 are described. Pure compounds derived from these reactions are presented, adding several new families to the library of fluorous PAH derivatives. Unique reactivities and interesting potential applications are discussed for several of these families. Solid-state packing and electronic properties are analyzed for selected derivatives. A particularly promising family of fluorous acceptors is presented and analyzed in greater depth in Chapter 3. It is based on the substrate phenazine (PHNZ). This family of molecules is notable because several derivatives exhibit enhanced acceptor strength and linearly-fused molecular structures resembling the acene class of PAHs, a high performing class of materials widely used in organic electronics. Results suggest that the molecules investigated in this chapter would be suitable for applications as air-stable n-type semiconductors in electronic devices. Finally, in Chapter 4, the characterization of a family of trifluromethylated acridine (ACRD) derivates is described. This investigation yields new insights into the reactivity of ACRD. Furthermore, detailed structural, spectroscopic and electronic property analysis combined with computational data revealed that not only the number of substituents, but also the position of substituents affects electronic energy levels. This finding not only expands basic understanding of how molecular structure affects electronic properties of PAHs, but also provides a valuable new tool for molecular design of acceptors with desirable properties.Item Open Access Synthesis of fluoromodified carbon rich electron acceptors and exploration of their structural, electronic, and device properties(Colorado State University. Libraries, 2020) DeWeerd, Nicholas J., author; Strauss, Steven H., advisor; Shores, Matthew P., committee member; Ackerson, Chris J., committee member; McCullagh, Martin J., committee member; Gelfand, Martin P., committee memberThe electronic and structural characterization of fluoro-modified carbon-rich compounds is critical to the successful implementation of these materials by physicists, biochemists, materials scientists, medicinal chemists, and most significantly for this work, organic electronics chemists. By adding powerful electron-withdrawing groups, the electron acceptor and solid-state structural properties of carbon rich substrates such as polyaromatic hydrocarbons (PAHs) and fullerenes can be improved, making these derivatives attractive semiconductor materials for organic electronics applications. This work will discuss research which has focused on expanding the library of electron acceptor compounds, elucidating the electronic and structural properties of those compounds, and exploring their physicochemical properties, focusing on properties that are important for the performance of organic electronic devices. This was accomplished by exploring reaction conditions which had not been previously reported at pressures and temperatures exceeding the operational limits of conventional reactors, developing purification methods that allow for chromatographic separation of constitutional isomers, and structural characterization of those purified materials by mass spectrometry, NMR, and most importantly X-ray crystallography. As a complement to this research, the stability of organic electronic active layers was studied to better understand how organic semiconductor active layer's degradation affects device performance over time and to better inform which active layer material properties should be pursued. Based on those findings and literature precedent, one family of compounds, C60 and C70 fauxhawk fullerenes, found to have favorable characteristics were then utilized in OFET devices as n-type semiconductors resulting in record-setting charge carrier mobilities.Item Open Access Synthesis, properties and applications of single-component anion-exchange materials(Colorado State University. Libraries, 2009) Caamaño, Samira, author; Strauss, Steven H., advisorSeveral tetraalkylated ferrocenium salts and neutral modified ferrocenes, both new and previously synthesized, were studied in detail. Some of these salts have been used in the past as anion-exchange extractants for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Different crystallographic, electrochemical and spectroscopic parameters were analyzed to study properties like cation size and its effect in selectivity, morphology of thin films made from these salts, both in the surface and in the bulk of the film, and film changes with time. It was found that when relative cation sizes are compared for different cations in these salts, the size increases in one dimension, which affects ion-exchange selectivity depending on what the non-aqueous phase containing the extractant is (either a water-immiscible solvent, a three-dimensional thin film or a monolayer self-assembled on an electrode surface). The effect of C-H...O hydrogen bonding in the cation-anion interactions was investigated. A model was proposed for the structure of thin films of a particular type of the ferrocenium salts, which was based on atom distances from the crystallographic data. Atomic force microscopy was used to study the morphology of surfaces of thin films, which had never been done before; the results were consistent with the hypothesis that there is a clear difference in the way that organic solutions of ferrocenium+NO 3- and ferrocenium+ClO 4- arrange molecularly as solvent evaporates, forming very different thin films.Item Open Access Synthesis, properties and applications of single-component anion-exchange materials(Colorado State University. Libraries, 2009) Caamaño, Samira, author; Strauss, Steven H., advisor; Meersmann, Thomas, committee member; Rickey Dawn, committee member; Elliott, Cecil Michael, committee memberSeveral tetraalkylated ferrocenium salts and neutral modified ferrocenes, both new and previously synthesized, were studied in detail. Some of these salts have been used in the past as anion-exchange extractants for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Different crystallographic, electrochemical and spectroscopic parameters were analyzed to study properties like cation size and its effect in selectivity, morphology of thin films made from these salts, both in the surface and in the bulk of the film, and film changes with time. It was found that when relative cation sizes are compared for different cations in these salts, the size increases in one dimension, which affects ion-exchange selectivity depending on what the non-aqueous phase containing the extractant is (either a water-immiscible solvent, a three-dimensional thin film or a monolayer self-assembled on an electrode surface). The effect of C–H...O hydrogen bonding in the cation–anion interactions was investigated. A model was proposed for the structure of thin films of a particular type of the ferrocenium salts, which was based on atom distances from the crystallographic data. Atomic force microscopy was used to study the morphology of surfaces of thin films, which had never been done before; the results were consistent with the hypothesis that there is a clear difference in the way that organic solutions of ferrocenium+NO3- and ferrocenium+ClO4− arrange molecularly as solvent evaporates, forming very different thin films. The use of an ATR-FTIR technique previously developed for the detection and quantification of anionic pollutants was investigated and optimized for new sample volumes, film thicknesses and analytes. Multiple-anion detection in aqueous media was examined. Among the new analytes studied was dodecylsulfate, (DDS−), the anion in the detergent sodium dodecylsulfate (SDS). These studies constituted a novel application of the ATR-FTIR spectroscopy technique in heart-valve research, which uses the detergent to decellularize tissue samples with the objective of preparing biological scaffolds free of cytotoxicity. A new ferrocene salt containing a nitrogen atom, which bears the positive charge of the cation, was successfully synthesized. This compound displayed better stability in biological solutions than other ferrocenium salts used previously. The use of this compound aided in answering the question of whether SDS leaches out of SDS-treated tissues after a soaking regime has been implemented: SDS does leach from treated tissues in potentially cytotoxic concentrations which are dependent on the initial treatment. It was also discovered that SDS leaches both as a free anion and, in initial stages of the soaking regime, complexed to other species. A new method was developed to detect and quantify anions in aqueous samples. This method also mitigated instability issues present in the use of certain ferrocenium salts and opened doors for conventional FTIR quantification of species using this kind of extractant. The synthesis of [35S]SDS was evaluated by successfully synthesizing SDS in the Strauss Research Group laboratories, using standard starting materials, one of which (H2SO4) can be obtained in its radioactively labeled form. A long term objective of this synthesis was to eventually quantify [35S]SDS directly in [35S]SDS-treated tissue samples, after a soaking regime, using beta scintillation counting.Item Open Access Trifluoromethylated fullerenes and polycyclic aromatic hydrocarbons and anaerobically milled silicon nanoparticles(Colorado State University. Libraries, 2015) Castro, Karlee P., author; Strauss, Steven H., advisor; Reynolds, Melissa M., committee member; Farmer, Delphine K., committee member; McCullagh, Martin J., committee member; Ramsdell, Howard S., committee memberWell characterized molecules and materials are essential to understand trends and predict future performance. Fundamental studies provide information about molecular properties which may be useful in other applications such as electronic devices. The focus of this dissertation is the characterization of three different classes of molecules/materials with the goal of understanding the fundamental underlying reasons for any trends observed. The first chapter of this dissertation examines the photophysical properties of C70(CF3)n (n = 8 or 10) molecules. Four of the compounds exhibited quantum yields higher than for any previously reported C70 derivative and three exceeded 0.24, the highest fluorescence quantum yield for any fullerene or fullerene derivative. A difference in the location of only one CF3 group in C70(CF3)8 and C70(CF3)10 isomers resulted in 200-fold and 14-fold increases in fluorescence quantum yields respectively. The isomer of C70(CF3)10 with the highest fluorescence quantum yield (0.68 in toluene) also exhibited the longest fluorescence lifetime (51 ns). Formation of the S1 state in one of the C70(CF3)10 isomers occurred within 0.6 ps and its nanosecond-long decay was monitored by ultrafast transient absorption spectroscopy. Time-dependent density functional theory calculations provide a physically meaningful understanding of the photophysical properties. High fluorescence quantum yields are correlated with high oscillator strengths for the S0→S1 transition, large ΔS1−T1 energy gaps, and small spatial extension of the S0→S1 excitation. The second chapter of this dissertation explores trifluoromethyl derivatives of polycyclic aromatic hydrocarbons (PAH(CF3)n). First, the effects of PAH size and shape on the product distribution are examined. Second, the electronic properties, including reduction potential and gas-phase electron affinity, are examined. Third, the influence of number and orientation of the CF3 groups on the crystalline morphologies of these compounds is explored. Finally, charge-transfer complexes made with PAH(CF3)n molecules mixed with PAHs are prepared and examined spectroscopically and crystallographically. From this work it was determined that when PAHs with 8–10 substitutable carbons are reacted with at least 10 equivalents of CF3I gas the PAH(CF3)n products had n values of 4–6 regardless of the size or shape of the PAH core. The reduction potential and gas-phase electron affinity exhibit a regular, incremental increase as a function of the number of trifluoromethyl groups. The number and position of CF3 groups influences the π-π stacking and crystalline morphologies and typically the more CF3 groups added, the lower the intermolecular overlap. Charge-transfer complexes made from mixing PAH(CF3)n and PAH form mixed stacks in the solid-state and exhibit weak association constants in solution. The third chapter of this dissertation examines the effects of oxygen and aromatic molecules on stirred media milling of silicon. Metallurgical-grade silicon was wet-milled in a stirred media mill to produce nanoparticles. Several milling fluids, additives, and milling parameters have been tested and compared between aerobic and anaerobic milling. It was determined that oxygen and aromatic molecules serve as surface passivating additives and lead to higher specific surface areas, indicating smaller particles. Particle amorphization occurs rapidly in a stirred media mill, within two hours crystallite size is on the order of 2-50 nm regardless of whether surface passivating additives are present. In all milling experiments, even in the presence of oxygen, new Si–C bonds are formed, the most Si–C bonds are formed when aromatic molecules are present during the milling process.