4H-Pyran-4-ylidenes: Strong Proaromatic Donors for Organic Nonlinear Optical Chromophores

作者：Andreu Raquel; Carrasquer Laura; Franco Santiago; Garin Javier^*; Orduna Jesus; Martinez de Baroja Natalia; Alicante Raquel; Villacampa Belen; Allain Magali

来源：Journal of Organic Chemistry, 2009, 74(17): 6647-6657.

DOI：10.1021/jo901142f

Merocyanines where a polyenic spacer separates a 4H-pyran-4-ylidetic moiety and different strong organic acceptors have been synthesized. According to NMR studies and X-ray diffraction data, these compounds have weakly alternated structures and remarkably zwitterionic ground states, with a partial aromatic character that is compared to those of other pyran derivatives. The proaromaticity of the 4H-pyran-4-ylidene donor lies behind the cyanine-like behavior and low (positive or negative) second-order optical nonlinearities of the shorter derivatives. On the other hand, lengthening the pi-spacer gives rise to rapidly increasing mu beta(1907) values up to 17,400 x 10(-48) esu.

• 出版日期2009-9-4