Synthesis and characterization of thiol-stabilized gold nanoparticles appended to bis(pyrazole) pyridine for fabrication of rectangular nano/microstripes and their spin crossover and SERS studies

Abstract

We report the synthesis and characterization of thiol-stabilized gold nanoparticles (AuNPs), functionalized with bis(pyrazole)pyridine ligands (L4 and 10), and their subsequent assembly into rectangular nano/microstripes using a lithographically controlled wetting (LCW) technique. The resulting microstructured patterns, with widths of ∼2 μm and heights of 150–200 μm, were employed to simultaneously explore spin crossover (SCO) behavior and surface-enhanced Raman scattering (SERS) properties. Compound 10 exhibited SCO behavior with a molar magnetic susceptibility (χT) of ∼3.3 emu K mol⁻¹ at 320 K. AuNPs of spherical, cubic, and triangular morphologies were synthesized and characterized by transmission electron microscopy (TEM), and their shape-dependent surface plasmon resonance (SPR) features were analyzed via UV-vis spectroscopy. Further characterization was done using ¹H NMR, Raman spectroscopy, and atomic force microscopy (AFM). These nanostructures enable to combine magnetic and plasmonic characteristics in a single device.