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Synthesis, Crystal Structures, Linear and Nonlinear Optical Properties, and Theoretical Studies of ( p ‐R‐Phenyl)‐, ( p ‐R‐Phenylethynyl)‐, and ( E ) ‐ [2‐( p ‐R‐Phenyl)ethenyl]dimesitylboranes and Related Compounds
Author(s) -
Yuan Zheng,
Entwistle Christopher D.,
Collings Jonathan C.,
AlbesaJové David,
Batsanov Andrei S.,
Howard Judith A. K.,
Taylor Nicholas J.,
Kaiser Hanns Martin,
Kaufmann Dieter E.,
Poon SukYue,
Wong WaiYeung,
Jardin Christophe,
Fathallah Sofiane,
Boucekkine Abdou,
Halet JeanFrançois,
Marder Todd B.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200501096
Subject(s) - bathochromic shift , substituent , chemistry , phenylacetylene , crystallography , crystal structure , stereochemistry , excited state , medicinal chemistry , fluorescence , physics , organic chemistry , quantum mechanics , nuclear physics , catalysis
The ( p ‐R‐phenyl)dimesitylboranes (R=Me 2 N, MeO, MeS, Br, I), ( p ‐R‐phenylethynyl)dimesitylboranes (R=Me 2 N, MeO, MeS, H), ( E ) ‐ [2‐( p ‐R‐phenyl)ethenyl]dimesitylboranes (R=Me 2 N, H 2 N, MeO, MeS, H, CN, NO 2 ), ( E ) ‐ [2‐(2‐thienyl)ethenyl]dimesitylborane, and ( E ) ‐ [2‐( o‐ carboranyl)ethenyl]dimesitylborane have been prepared through the reaction of the appropriate p ‐R‐phenyl‐ and p ‐R‐phenylethynyllithium reagents with dimesitylboron fluoride and by hydroboration of the appropriate p ‐R‐phenylacetylene, 2‐ethynylthiophene, and o ‐ethynylcarborane with dimesitylborane. Their UV/Vis absorption and emission spectra have been recorded in a range of solvents with the fluorescence maxima of the donor‐substituted compounds in particular exhibiting large bathochromic shifts in highly polar solvents, indicative of charge transfer leading to large dipole moments in the excited state. The molecular structures of the ( p ‐R‐phenyl)dimesitylboranes (R=Me 2 N, MeO, MeS, Br, I), the ( E ) ‐ [2‐( p ‐R‐phenyl)ethenyl]dimesitylboranes (R=Me 2 N, H 2 N MeO, MeS, H), ( p ‐R‐phenylethynyl)dimesitylborane (R=Me 2 N), and ( E )‐[2‐(2‐thienyl)ethenyl]dimesitylborane, which have been determined from single‐crystal X‐ray diffraction measurements, offer evidence of increased conjugation in the ground state with increased donor strength of the R substituent. Their first‐ and second‐order molecular hyperpolarizabilities have been obtained from EFISH and THG measurements, the first‐order hyperpolarizabilities being largest for the strongest R‐substituent donors. AM1 calculations have been performed on these compounds, showing reasonable agreement with the experimentally obtained bond lengths and hyperpolarizabilities, as well as on several related hypothetical compounds containing multiple CC bonds, most of which are proposed to have even larger hyperpolarizabilities.