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Heterogeneous Rotational Diffusion Of A Fluorescent Probe In Lipid Monolayers, Christina M. Othon
Heterogeneous Rotational Diffusion Of A Fluorescent Probe In Lipid Monolayers, Christina M. Othon
Christina M Othon
The rotational correlation time of the lipid probe 1-palmitoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine (NBD-PC) is measured using fluorescence anisotropy for two lipid species. We measure the rotational diffusion in a monolayer of 1,2-Didecanoyl-sn-glycero-3-phosphocholine (DPPC) which displays a phase transition at room temperature from the liquid expanded to the liquid-condensed phase. The constant rotational diffusion of the probe throughout the phase transition reflects the measurement of dynamics in only the liquid-expanded phase. We contrast the dynamic changes during this phase coexistence to the continuous density increase observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at room temperature. We observe a non-exponential decay of the probe diffusion consistent with heterogeneity …
Charge Transfer Assisted By Collective H-Bonding Network Dynamics, Omar F. Mohammed, Christina M. Othon, Oh-Hoon Kwon, Ahmed H. Zewail
Charge Transfer Assisted By Collective H-Bonding Network Dynamics, Omar F. Mohammed, Christina M. Othon, Oh-Hoon Kwon, Ahmed H. Zewail
Christina M Othon
Although there have been numerous studies of solvation, the role of solvent specific and collective interactions, especially for charge-transfer processes, remains difficult to unravel. Here, we report, using femtosecond fluorescence up-conversion and steady-state spectroscopic measurements, studies of well-designed single-sited formylperylene (FPe) in binary solvents. One of the solvents (methanol, MOH) can selectively hydrogen (H) bond to the carbonyl (C=O) site, while the other (acetonitrile, ACN) cannot, but both have similar polarity ( for MOH and for ACN). The results reveal that ultrafast charge transfer from the perylene unit to the carbonyl group of FPe is facilitated by site-specific H-bonding interactions …