A Ni(II) sulfamerazine complex with strong telecom-band linear dichroism: Synthesis, crystal structure, Hirshfeld surfaces, NLO properties and SOS optical modeling

Abstract

In this work, a new sulfamerazine-based Ni complex was synthesized, namely tris(ethylenediamine-κ2N, N’)-nickel(II) bis(sulfamerazinate) hydrate (abbreviated as compound (I) herein), and characterized by single-crystal X-ray diffraction. Compound (I) crystallizes in the monoclinic C2/c space group. A detailed Hirshfeld surface (HS) analysis of (I) showed that its crystal structure is stabilized by the presence of O─H∙∙∙O, O─H∙∙∙N, N─H∙∙∙O and N─H∙∙∙N H-bonds, in addition to C─H∙∙∙H─C and C─H···π intermolecular interactions. The theoretical modeling revealed the significant influence of the crystalline environment, with a molecular dipole moment increase of 20.7%. This stabilization is also reflected in the global reactivity descriptors. A sum-over-states (SOS) model predicted a strongly anisotropic linear optical response in the telecom window. At 1550 nm, the absorption coefficients (αa ≈ 5.2 × 10² cm⁻¹, αb ≈ 1.1 × 10² cm⁻¹, and αc ≈ 3.7 × 10¹ cm⁻¹) enable the design of thin single-crystal dichroic polarizers. Overall, (I) combines a stabilized electronic structure with strong linear dichroism, identifying it as a robust candidate for dichroic polarizers in the telecom band, while showing a competitive third-order nonlinearity.