Dissertation Defense: Lili Qiu
Candidate Name: Lili Qiu
Advisor: Miklos Kertesz, Ph.D.
Title: Unusual Carbon-Carbon Bonding in ?-Conjugated Cyclic Hydrocarbons by High Pressure and in Quinonoid Diradicals by Mild Stimuli
A series of [n]-Cycloparaphenylenes ([n]CPPs, n=5, 6, 7, 8, 9, 10 and 12) were subjected to ambient and high pressures and their in situ Raman spectra obtained. Density functional theory modeling provides fundamental interpretations of the spectral band shifts as a function of pressure. This thesis provides atomic level insights into the change of the aromatic vs quinonoid structures of the benzene-like rings and how, consequently, cyclic p-conjugation and intramolecular strain are modulated. The systematic geometric changes involve molecular flattening accompanied by changes of bond length alternation and inter-phenyl torsions. The presented analysis sheds light on the modification of ring-strain to respond to high pressure under the two different and prevalent crystal packing environments of [n]CPPs, either herringbone or tubular packing.
Tuesday, June 5 at 10:00am to 12:00pm
Regents Hall, 451
3700 O St. NW