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Theoretical Investigation of Stilbene as Photochromic Spin Coupler

DSpace at IIT Bombay

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Title Theoretical Investigation of Stilbene as Photochromic Spin Coupler
 
Creator PAL, AK
HANSDA, S
DATTA, SN
ILLAS, F
 
Subject INTRAMOLECULAR MAGNETIC INTERACTION
DENSITY-FUNCTIONAL THEORY
TRANSITION-METAL DIMERS
NITRONYL-NITROXIDE
IMINO-NITROXIDE
AB-INITIO
GEOMETRY OPTIMIZATION
ELECTRONIC-STRUCTURE
MO CALCULATIONS
FREE-RADICALS
 
Description Density functional theory (DFT) based calculations are used here to investigate the magnetic behavior, spectroscopic transitions, and possible photomagnetic properties of stilbene derivatives using photochromicity of cis- and trans-forms of the parent molecule. Nitronyl nitroxide (NN), iminonitroxide (IN), tetrathiafulvalene cation (TTF), and verdazyl (VER) are used as monoradical centers at the p, p positions. The B3LYP functional with the usual broken symmetry approach and a sufficiently large basis set is chosen to obtain reliable estimates of the intramolecular exchange coupling constants W. It is found that, with stilbene as a spacer, the coupling of TTF with NN, IN, and VER is always antiferromagnetic with J being generally large and negative. Although J values obtained for cis- and transforms are both negative, the difference in J values is quite large. Spectroscopic transition energies and corresponding oscillator strengths of cis- and trans-stilbene diradicals are estimated by time dependent (TD)-DFT calculations using the same functional Interestingly, the spectral features of the diradicals are similar to those of cis- and trans-stilbene, which suggests that stilbene diradicals would have good photoswitching properties. Finally, we show that, when these diradicals are placed in a matrix, photochromicity would be accompanied by a significant change in paramagnetic susceptibility.
 
Publisher AMER CHEMICAL SOC
 
Date 2014-10-15T13:53:00Z
2014-10-15T13:53:00Z
2013
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY A, 117(8)1773-1783
http://dx.doi.org/10.1021/jp306715y
http://dspace.library.iitb.ac.in/jspui/handle/100/15034
 
Language en