The tetra(4-methoxyphenyl)phosphonium iodide C 28 H 28 O 4 PI (MOPPI) is a crystal built up with quasi octupolar tetrahedral chromophores having quadratic nonlinear optical (NLO) properties. The calculated values of the highest tensor component β xyz for the hyperpolarizable chromophore, in its most stable S 4 geometry, vary from 4.23 to 9.23 × 10 - 30 esu, depending on the methods of calculation. Given the linear absorption maximum at 255 nm, this reveals a good hyperpolarizability−transparency tradeoff. The crystal is twinned by merohedry. The crystal structure was solved until a reliability factor R = 0.048 using 2189 untwinned reflections. The material crystallizes in the noncentrosymmetric orthorhombic space group P 2 1 2 1 2 1 with Z = 4 and the unit cell parameters a = b = 10.131(3) Å, c = 25.682(6) Å. The cation−anion arrangement corresponds to a NaCl-type model weakly distorted. Signal of second harmonic of a crystalline powder at 1.06 μm is nearly equivalent to that of urea.
No takes yet. Share an insight, caveat, or question.
Bourgogne et al. (2000) studied this question.