Effect of Molecular Polarization on Bond-Length Alternation, Linear Polarizability, First and Second Hyperpolarizability in Donor-Acceptor Polyenes as a Function of Chain Length

1995 ◽  
Vol 7 (1) ◽  
pp. 215-220 ◽  
Author(s):  
Christopher B. Gorman ◽  
Seth R. Marder
Keyword(s):  
Bond Length ◽  
Chain Length ◽  
Bond Length Alternation ◽  
Second Hyperpolarizability ◽  
Donor Acceptor

Large Quadratic Hyperpolarizabilities with Donor–Acceptor Polyenes Exhibiting Optimum Bond Length Alternation: Correlation Between Structure and Hyperpolarizability

1997 ◽  
Vol 3 (7) ◽  
pp. 1091-1104 ◽  
Author(s):  
M. Blanchard-Desce ◽  
V. Alain ◽  
P. V. Bedworth ◽  
S. R. Marder ◽  
A. Fort ◽  
...  
Keyword(s):  
Bond Length ◽  
Bond Length Alternation ◽  
Donor Acceptor

Structure-Property Relationships in Organic Nonlinear Optical Materials

1999 ◽  
Vol 561 ◽  
Author(s):  
Eric M. Breitung ◽  
Robert J. McMahon
Keyword(s):  
Bond Length ◽  
Optical Materials ◽  
Nonlinear Optical ◽  
Conformational Flexibility ◽  
Nonlinear Optical Materials ◽  
Structure Property ◽  
Bond Length Alternation ◽  
Design And Synthesis ◽  
Nlo Materials ◽  
Donor Acceptor

ABSTRACTTuning the degree of bond-length alternation in organic nonlinear optical materials is a powerful paradigm for the design of organic materials with large molecular hyperpolarizabilities (β). Several research groups have employed this paradigm in the design and synthesis of NLO materials incorporating donor-acceptor polyenes. Increased bond-length alternation in polyenes leads to decreased barriers to rotation about C=C bonds and, hence, increased conformational flexibility. Since the degree of bond-length alternation is solvent dependent, so is the degree of conformational flexibility. In an effort to probe the influence of conformational flexibility on NLO response, we synthesized a series of simple donor-acceptor polyenes that are either conformationally flexible (la, 2a, 3a) or rigid (1b, 2b, 3b). For each pair of molecules ZINDO sum-over-states calculations predict a larger value of βμ, for the conformationally flexible isomer, but EFISH measurements (CHCl3) display mixed results. Various explanations for this behavior will be considered.

Reduced bond length alternation and helical molecular orbitals in donor and acceptor substituted linear carbon chains

2018 ◽  
Vol 17 (08) ◽  
pp. 1850049 ◽  
Author(s):  
AbhayRam Balakrishnan ◽  
R. Shankar ◽  
S. Vijayakumar
Keyword(s):  
Bond Length ◽  
Molecular Electronics ◽  
Chain Length ◽  
Molecular Wires ◽  
Molecular Orbitals ◽  
Bond Length Alternation ◽  
Dft Methods ◽  
Carbon Chains ◽  
Donor And Acceptor ◽  
Molecular Orbital Analysis

Increasing chain length and end group substitution of polyynes play a crucial role in molecular electronics and nanomaterials. The studies on linear carbon chains are lesser when compared to other carbon allotropes like graphene, fullerenes, nanotube, etc. This prompted us to study the linear carbon chains of different lengths and substitutions. The electronic and optical properties of X–C[Formula: see text]–X ([Formula: see text]–15 and [Formula: see text], NH2, CN, OH) molecules have been studied by using CAM-B3LYP/6-31G* level of theory of DFT methods. Linear carbon chains with odd values of n show lower bond length alternation (BLA) values similar to that of cumulenes and may have metallic property, but the substitution of donor/acceptor molecules does not decrease the BLA significantly. Molecular orbital analysis of linear carbon chains shows that NH2 or NO2 substituted polyynes have helical molecular orbitals for smaller chain lengths which may make a good candidate for molecular wires in molecular devices. As the chain length increases, the helicity decreases and finally disappears. Also, it is seen that for smaller odd values of [Formula: see text] for donor, substituted polyynes have a singlet ground, whereas all the odd [Formula: see text] values of acceptor substitution have triplet ground state.

Direct observation of reduced bond-length alternation in donor/acceptor polyenes

1993 ◽  
Vol 115 (6) ◽  
pp. 2524-2526 ◽  
Author(s):  
Seth R. Marder ◽  
Joseph W. Perry ◽  
Bruce G. Tiemann ◽  
Christopher B. Gorman ◽  
Sandra Gilmour ◽  
...  
Keyword(s):  
Bond Length ◽  
Direct Observation ◽  
Bond Length Alternation ◽  
Donor Acceptor

A New Class of Cyanine-like Dyes with Large Bond-Length Alternation

2009 ◽  
Vol 131 (17) ◽  
pp. 6099-6101 ◽  
Author(s):  
Shino Ohira ◽  
Joel M. Hales ◽  
Karl J. Thorley ◽  
Harry L. Anderson ◽  
Joseph W. Perry ◽  
...  
Keyword(s):  
Bond Length ◽  
Bond Length Alternation ◽  
New Class

scholarly journals An investigation of the interrelationships between linear and nonlinear polarizabilities and bond-length alternation in conjugated organic molecules

1993 ◽  
Vol 90 (23) ◽  
pp. 11297-11301 ◽  
Author(s):  
C B Gorman ◽  
S R Marder
Keyword(s):  
Bond Length ◽  
Organic Molecules ◽  
Computational Method ◽  
Bond Length Alternation ◽  
Conjugated Molecules ◽  
Conjugated Organic Molecules ◽  
Alpha Beta ◽  
Relationship Of ◽  
The Relationship ◽  
Observable Parameter

A computational method was devised to explore the relationship of charge separation, geometry, molecular dipole moment (mu), polarizability (alpha), and hyperpolariz-abilities (beta, gamma) in conjugated organic molecules. We show that bond-length alternation (the average difference in length between single and double bonds in the molecule) is a key structurally observable parameter that can be correlated with hyperpolarizabilities and is thus relevant to the optimization of molecules and materials. By using this method, the relationship of bond-length alternation, mu, alpha, beta, and gamma for linear conjugated molecules is illustrated, and those molecules with maximized alpha, beta, and gamma are described.

Bond length alternation and aromaticity in large annulenes

1998 ◽  
Vol 108 (16) ◽  
pp. 6681-6688 ◽  
Author(s):  
Cheol Ho Choi ◽  
Miklos Kertesz
Keyword(s):  
Bond Length ◽  
Bond Length Alternation
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