Spin crossover self-assembled monolayer of a Co(II) terpyridine derivative functionalized with carboxylic acid groups

TL;DR

This paper reports the successful formation of a spin-crossover monolayer of a Co(II) terpyridine derivative on a surface, demonstrating a thermal spin transition confirmed by multiple spectroscopic techniques, marking a novel achievement in surface chemistry.

Contribution

First demonstration of an active spin-crossover monolayer directly assembled on a surface via wet chemistry, with confirmed spin transition behavior.

Findings

Monolayer grafted via carboxylate groups confirmed by spectroscopy.

Thermal spin transition observed in the monolayer.

First example of active SCO assembly in direct contact with a surface.

Abstract

The deposition of a monolayer by direct self-assembly from solution of an active spin-crossover (SCO) complex via chemisorption has been achieved starting from the perchlorate salt of Co(II) bis(4-(4-carboxyphenyl)-2,2:6,2-terpyridine). MALDI-TOF MS, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirm the presence of an intact monolayer of SCO molecules grafted through carboxylate groups to the Ag surface. Three different spectroscopic techniques (Raman, XPS and X-ray Absorption spectroscopy, XAS) evidence a thermal spin transition of such monolayer of molecules. To our knowledge, this is the first example of an active SCO assembly in direct contact with a surface obtained by wet chemistry.