New calixarenes for nonlinear optics: synthesis and conformation of functionalized p-nitrocalix[4]arenes

New functionalized p-nitrocalix[4]arenes have been synthesized. They adopt a cone conformation or the less common partial cone conformation both in solution and in the solid state. They can be used as intermediates or for second-order nonlinear optics (NLO). The structure of the 11,23-dinitro-26,28-dipropoxy-25,27-di-etoxycarbonylmethoxycalix[4]arene has been determined by X-ray crystallography. The NLO activity is consistent with the solid state and solution conformations.