02031nas a2200157   4500008004100000245010500041210006900146260000800215300001600223490000700239520144800246100001501694700001701709700002201726856012501748       2005                        eng d00aSynthesis, characterization, and hyperpolarizability measurements of main-chain azobenzene molecules0 aSynthesis characterization and hyperpolarizability measurements   cAUG  a4455–44680 v433 a<p>A series of new AB type azobenzene monomers based on various substituted phenols and higher order fused/extended aromatic rings were synthesized and their hyperpolarizability tensor β determined by hyper-Rayleigh scattering (HRS) measurement in methanol. The electron donor ([BOND]OH) and acceptor units ([BOND]COOH) were kept constant in the series, but the effective conjugation length was varied by varying the number and position of substituents as well as the number of aromatic rings. The effect of substitution of the phenolic ring on the β value was investigated and it was found to range from 15 × 10−30 to 42 × 10−30 esu. The effect of intramolecular hydrogen bonding on the nonlinear optical (NLO) property was also examined. The nonlinearity was in the following order of phenol derivative: α-naphthol &gt; phenyl phenol &gt; 2,6-dimethyl phenol &gt; o-cresol &gt; cardanol &gt; phenol &gt; β-naphthol. The unusually low values for the β-naphthol-based chromophore compared with its isomer (α-naphthol) could be rationalized based on hydrogen bonding of the o-hydroxyl group with the β nitrogen of the azo bridge. These azobenzene NLO chromophoric monomers were polymerized to form main-chain polymers with a head to tail structure. The polymers had high thermal stability and rather low solubility in common organic solvents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4455–4468, 2005</p>1 aSmitha, P.1 aAsha, S., K.1 aPillai, C., K. S.  uhttps://library.ncl.res.in/content/synthesis-characterization-and-hyperpolarizability-measurements-main-chain-azobenzene