Orientation of Second‐Harmonic‐Generation‐Active Phenylsulfonyl Chromophores Attached on Layered Lead(II) Phosphonates

The hydrothermal reactions of PbCl 2 or PbBr 2 with diethyl [(phenylsulfonyl)methyl]phosphonate afforded two lead(II) phosphonates with the formula [Pb 3 (Ph–SO 2 –CH 2 –PO 3 ) 2 X 2 (H 2 O)] [X = Cl ( 1 ) and Br ( 2 )]. The two compounds are isostructural and exhibit a lamellar structure in which the phenylsulfonyl chromophores orient unilaterally on the inorganic layer of [Pb 3 (PO 3 ) 2 X 2 (H 2 O)]. The acentric stacking of such layers results in their crystallization in the noncentrosymmetric Cc space group, and both compounds show second harmonic generation responses comparable to that of KDP (KH 2 PO 4 ).