Can Cu(II) ions be doped into the crystal structure of potassium hydrogen tartrate?

TL;DR

This paper demonstrates that Cu(II) ions cannot be doped into potassium hydrogen tartrate crystals due to differing ligand binding preferences, invalidating previous claims of copper doping in such crystals.

Contribution

It clarifies the binding modes of hydrogen tartrate with potassium and copper ions, disproving earlier claims of copper doping in potassium hydrogen tartrate crystals.

Findings

Cu(II) binds in bidentate mode, not octadentate

Doping of Cu(II) into potassium hydrogen tartrate is not feasible

Previous doping claims are invalid

Abstract

The differing binding preferences of the hydrogen tartrate ligand (HC4H4O6)- namely {\mu}7-octadentate mode for potassium ion and bidentate mode for cupric ion rules out the doping (incorporation) of any Cu(II) ion into the crystal structure of potassium hydrogen tartrate. Hence, the claim of growth of copper doped potassium hydrogen tartrate viz. K0.96Cu0.04C4H5O6 by Mathivanan and Haris, Indian J Pure App Phys 51 (2013) 851-859 is untenable.