The ability of 2,2′-bipyridine-bound copper(II) ions to quench the photoluminescence of hydrophobic CdSe quantum dots is used to create a novel, selective turn-on fluorescence cyanide sensor.

This feature article presents an overview of the types of hydrogen bonding interactions involving metal complexes and their functional effects. It shows with recent examples why hydrogen bonds have become a crucial functional and structural element in modern inorganic chemistry. The relevance of this combination in tackling current chemistry challenges such as energy production and the development of new materials and more effective catalysts, sensors and medicines is illustrated.

Introducing ligand based hydrogen bond donors to increase the activity of a mononuclear Zn(II) complex for catalysing phosphate ester cleavage can be a more effective strategy than making the dinuclear analogue.

Two strategies are described for the construction of extended arrays of transition metal-containing molecules linked via hydrogen bonds. The first approach connects the transition metal to the ligand bearing the hydrogen-bonding group(s) via a coordinative bond. Thus, coordination complexes with peripheral hydrogen-bonding functional groups constitute the (molecular) building blocks of the assembly. The ligands, substituted pyridines, have been selected to provide rigidity and thus permit the metal coordination geometry to guide the direction of propagation of the hydrogen-bonded links between building blocks. The second approach uses arenes bearing hydrogen-bonding functional groups, the arenes being π-bound to transition metals as is typical of sandwich and half-sandwich organometallic compounds. In the first approach the metal can be viewed as serving a directing role in propagation of the hydrogen bonded assembly. In the second, the metal can be thought of as a (potentially functional) appendage to an organic hydrogen-bonded array, where substituent position at the arene ring serves the directing role for propagation. Examples presented for discussion of the coordination chemistry approach are compounds of the form [PtL₄]X₂ (L = nicotinamide or isonicotinamide; X⁻ = Cl⁻ or PF₆ ⁻). Examples presented in the context of the organometallic approach are members of the series [Cr{η⁶-C₆H_6 − n(CO₂H)_n}(CO)₃], where n = 1–3.