Crystal engineering of urea α-network via I⋯O2N synthon and design of SHG active crystal N-4-iodophenyl-N′-4′-nitrophenylurea

Abstract

Crystalline nitrodiphenyl ureas adopt the N–H⋯O tape α-network only when stabilization accrues from the I⋯O₂N or CC–H⋯O₂N synthon, otherwise the urea⋯nitro motif is preferred; soft, weak interactions can direct polar self-assembly in strong N–H⋯O hydrogen-bonded crystals.