57247-77-5Relevant academic research and scientific papers
Tuning HOMO-LUMO levels: Trends leading to the design of 9-fluorenone scaffolds with predictable electronic and optoelectronic properties
Eakins, Galen L.,Alford, Joshua S.,Tiegs, Brandon J.,Breyfogle, Bryan E.,Stearman, Chad J.
experimental part, p. 1119 - 1128 (2012/03/22)
Highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) tuning is an important consideration in the development of organic-based semiconducting materials. A study of the specific effects and overall trends for the HOMO-LUMO tuning of a diverse series of 9-fluorenones by means of extended conjugation and substituent effects is described. Trends were explored in a range of compounds, beginning with structures having highly electron-withdrawing substituents and progressing to structures having highly electron-donating substituents. Compounds with an incremental increase in conjugation were also examined. Electrochemical and optical measurements were used to calculate the HOMO-LUMO levels and HOMO-LUMO bandgap (HLG) for each structure. Results from both methods were compared and correlated with the differences in molecular structure. Increasing the electron-donating character of the substituents was observed to decrease the HLG and increase the energy levels of the HOMO and the LUMO, whereas an increase in the electron-withdrawing character produced the opposite results. Increasing conjugation decreased the HLG, increased the HOMO energy level, but decreased the LUMO energy level. Spectroscopic evidence of substituent influence on the carbonyl suggests that substituents directly impact the HLG by influencing the availability of nonbonding electrons within the carbonyl, which impacts the probability of an nπ* transition. The data presented not only elaborate on the HOMO-LUMO tuning of 9-fluorenone systems but also enable the consideration of 9-fluorenones as analogous models for HOMO-LUMO tuning in other more complex polyaromatic systems such as bifluorenylidenes. These trends may provide insight into developing materials with specifically tuned HLGs and HOMO-LUMO levels for a variety of applications. Copyright
Al(OTf)3 as a highly efficient catalyst for the rapid acetylation of alcohols, phenols and thiophenols under solvent-free conditions
Kamal, Ahmed,Khan, M. Naseer A.,Reddy, K. Srinivasa,Srikanth,Krishnaji
, p. 3813 - 3818 (2008/02/06)
Aluminium triflate (0.01-0.1 mol %) was found to be an efficient catalyst for the acylation of alcohols, phenols, thiols and sugars with acetic anhydride in high yields under solvent-free conditions in a short reaction time at room temperature. Racemization of optically active alcohols and epimerization of sugars were not observed. The acylation efficacy of various acyl donors was also investigated.
Asymmetry in molecular ordering in the nematic phase: DMR study
Wu, Bao-Gang,Ziemnicka, Barbara,Doane, J. William
, p. 1373 - 1382 (2007/10/02)
Deuterium nuclear magnetic resonance (2H-NMR) was performed on the rigid perdeuterated fluorene segment of the compound 2-fluorenyl-4'-tetradecyloxy benzoate (FLOC 14-d9) tounambiguously measure the order parameter U which reflects the degree of asymmetric ordering of the molecule in the nematic liquid crystalline phase.Measurements of U showed this parameter to be finite at all temperatures in the nematic phase indicative of the uniaxial phase U2 described in the Allender-Lee generalized Landau theory.Mixtures of FLOC 14-d9 with compounds consisting of molecules more cylindrical in shape were also studied to examine their effect on the parameter U.Other parameters such as the degree of order S and the orientation of the principal axes of the Maier-Saupe order matrix were measured and are discussed.
