Structural, optical, and electrochemical properties of a new 1D copper (II) halometalate for highly sensitive dopamine detection

Abstract

A new one-dimensional (1D) copper(II) halometalate, [Cu(κ²-Cl)₂(η¹-4-I-Pz)₂] (4-I-Pz = 4-Iodopyrazole), was synthesized via a Schlenk method and structurally characterized by singlecrystal X-ray diffraction. The compound consists of infinite Cu-Cl-Cu chains featuring Jahn-Teller-distorted Cu(II) centers in elongated octahedral environments. The 1D architecture is reinforced by synergistic I•••I and I•••Cl halogen interactions together with π-π stacking, generating a robust supramolecular framework. Diffuse reflectance spectroscopy combined with Kubelka-Munk and Tauc analyses reveals an indirect optical band gap of 2.23 eV and a noticeable Urbach tail, highlighting the influence of structural anisotropy on its electronic properties. Optical investigations further evidence ligand-to-metal charge transfer and characteristic Cu(II) d-d transitions. When employed as a glassy carbon electrode modifier, the material exhibits excellent electrocatalytic activity toward dopamine oxidation, delivering a low detection limit of 0.01 μM, two linear ranges (0.01-1 and 1-10 μM), high selectivity, and recovery values of 96.7-102% in human serum. These findings establish a clear structureproperty-function relationship and demonstrate the potential of 1D copper halometalates as multifunctional materials for optoelectronic and electrochemical sensing applications.