Rheological and photophysical investigations of chromonic-like supramolecular mesophases formed by luminescent iridium(III) ionic complexes in water

ABSTRACT

Luminescent complexes with general formula [(C^N)₂Ir(N^N)]OCOCH₃, where C^N = 2-phenylpyridine (ppy) and N^N = 2,2ʹ-bipyridine (bpy), self-assemble into ordered ‘soft’ viscous mesophases of chromonic type. By changing the ancillary ligand with 1,10-phenanthroline (phen), a new mesomorphic complex was obtained. The self-assembly into ordered liquid crystalline phases of chromonic type in water was investigated by comprehensive rheological and photophysical studies. By changing the ancillary ligand bpy with phen, assembly into smaller, more symetric aggregates is favoured, resulting in lower viscosity and more dynamic mesophase.

Graphical Abstract

KEYWORDS:

• Iridium(III) complexes
• chromonic-like liquid crystals
• rheology
• photophysics
• water self-assembling

Acknowledgements

This work was supported by the European Community’s Seventh Framework Program (FP7 2007–2013) through the MATERIA project (PONa3_00370) and MATELIOS (PON03PE_00092), by the Ministero dell’Istruzione, dell’Università e della Ricerca through Italian PRIN 2012 (N. 2012JHFYMC) and by Regione Calabria (Italy) through POR CALABRIA FESR 2007/2013, ASSE I. I.A. thanks Carla Bertucci and Sabrina Stillo for their help in the synthesis. E. I. Sz. and C. C. dedicate this work to the 150th anniversary of the Romanian Academy.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Regione Calabria (Italy) [POR CALABRIA FESR 2007/2013, ASSE I]; FP7 2007-2013 [MATELIOS (PON03PE_00092)]; FP7 2007–2013 [MATERIA project (PONa3_00370)]; Ministero dell’Istruzione, dell’Università e della Ricerca [Italian PRIN 2012 (N. 2012JHFYMC)].