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]_n (4-I-Pz = 4-iodopyrazole), was synthesized via a Schlenk method and structurally characterized by single-crystal 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 structure–property–function relationship and demonstrate the potential of 1D copper halometalates as multifunctional materials for optoelectronic and electrochemical sensing applications.