Document Detail

Impact of Electronic Coupling, Symmetry and Planarization on One- and Two-Photon Properties of Triarylamines with One, Two or Three Diarylboryl Acceptors.
MedLine Citation:
PMID:  22429020     Owner:  NLM     Status:  Publisher    
We have performed a study of the one- and two-photon absorption properties of a systematically varied series of triarylamino-compounds with one, two, or three attached diarylborane arms arranged in linear dipolar, bent dipolar, and octupolar geometries. Two-photon fluorescence excitation spectra were measured over a wide spectral range with femtosecond laser pulses. We found that, on going from the single-arm to the 2- and 3-arm systems, the peak in two-photon absorption (2PA) cross section is suppressed by factors of 3 - 11 for the lowest excitonic level associated with the electronic coupling of the arms, whereas it is enhanced by factors of 4 - 8 for the higher excitonic level. These results show that the coupling of arms redistributes the 2PA cross section between the excitonic levels in a manner that strongly favors the higher-energy excitonic level. The experimental data on one- and two-photon cross sections, ground- and excited-state transition dipole moments, and permanent dipole moment differences between the ground and lowest excited states were compared to the results of obtained from a simple Frenkel exciton model and from highly-correlated quantum-chemical calculations. It has been found that planarization of the structure around the triarylamine moiety leads to a sizable increase in peak 2PA cross section for the lowest excitonic level of the 2-arm system, whereas for the 3-arm system the corresponding peak was weakened and shifted to lower energy. Our studies show the importance of the inter-arm coupling, number of arms, and structural planarity on both the enhancement and suppression of two-photon cross sections in multi-arm molecules.
Nikolay Makarov; Sukrit Mukhopadhyay; Yesudas Kada; Jean-Luc Bredas; Joseph W Perry; Agnieszka Proń; Milan Kivala; Klaus Mullen
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-19
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  -     ISSN:  1520-5215     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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