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

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.

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

Approximate Molecular Orbital Theory: The Hückel/Tight-binding Model

2020 ◽  
pp. 231-245
Author(s):  
Jochen Autschbach
Keyword(s):  
Bond Length ◽  
Molecular Orbital ◽  
Tight Binding ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Bond Length Alternation ◽  
Binding Model ◽  
Linear Polyenes ◽  
Benzene Structure ◽  
Cyclic Polyenes

Huckel molecular orbital (HMO) theory is a simple approximate parameterized molecular orbital (MO) theory that has been very successful in organic chemistry and other fields. This chapter introduces the approximations made in HMO theory, and then treats as examples ethane, hetratriene and other linear polyenes, and benzene and other cyclic polyenes. The pi binding energy of benzene is particularly large according to HMO theory, rationalizing the special ‘aromatic’ behaviour of benzene. But there is a lot more to benzene than that. It is shown that the pi bond framework of benzene would rather prefer a structure with alternating single and double C-C bonds, rather than the actually observed 6-fold symmetric structure where all C-C bonds are equivalent. The observed benzene structure is a result of a delicate balance between the tendencies of the pi framework to create bond length alternation, and the sigma framework to resist bond length alternation.

scholarly journals The Ultrafast Photoisomerizations of Rhodopsin and Bathorhodopsin Are Modulated by Bond Length Alternation and HOOP Driven Electronic Effects

2011 ◽  
Vol 133 (10) ◽  
pp. 3354-3364 ◽  
Author(s):  
Igor Schapiro ◽  
Mikhail Nikolaevich Ryazantsev ◽  
Luis Manuel Frutos ◽  
Nicolas Ferré ◽  
Roland Lindh ◽  
...  
Keyword(s):  
Bond Length ◽  
Electronic Effects ◽  
Bond Length Alternation
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