History and fundamentals of molecular photochromism

Abstract

Photochromic molecules reversibly change their colour upon exposure to light. The increasing need for smart materials in the real world, coupled with progress in synthetic chemistry, fast spectroscopic techniques, and theoretical power in research laboratories, have seen research in organic photochromism accelerate over the past few decades. In this Primer Review, the topic of organic photochromism is introduced. The fundamental concepts and histories are given to contextualise this field. Moreover, key photochromic molecules and selected applications are showcased to provide the interested reader with an entry to this fascinating field of science and emerging technology.

Steric Bulk‐Dependent Photoresponse of Sulfonamide Azobenzene Ligand in Arene Ruthenium(II) Complexes

“…The potential applications of these molecular systems cover a variety of fields, such as controlling optical, redox and magnetic properties, self-association in both solution and solid state, biological activity and chemical reactivity, and notably catalytic behavior. [1][2][3][4][5][6] Among this class of photoresponsive molecules, ligands derived from azobenzene [4,[7][8][9][10][11][12][13][14][15] and to a lesser extent aromatic imines, [16] play a special role because the N=N (or C=N) bond can function not only as the photoisomerizing unit, but also as the coordinating site. Consequently, these complexes undergo strong geometry modification in the vicinity of the metal center, which is likely to modulate molecular properties to a large extent.…”

“…Metal complexes bearing photochromic ligands, that can reversibly change between two different states in response to light, have attracted growing research interest recently due to the possible tuning of their structure and properties using a non‐invasive stimulus. The potential applications of these molecular systems cover a variety of fields, such as controlling optical, redox and magnetic properties, self‐association in both solution and solid state, biological activity and chemical reactivity, and notably catalytic behavior [1–6] . Among this class of photoresponsive molecules, ligands derived from azobenzene [4,7–15] and to a lesser extent aromatic imines, [16] play a special role because the N=N (or C=N) bond can function not only as the photoisomerizing unit, but also as the coordinating site.…”

Celebrating RACI and Academy of Science awards 2022–23

“…The authors conclude that, although several types of organic photochromes have been studied extensively, numerous potential applications are waiting to be explored. 3 Paul L. Burn (The University of Queensland), winner of the Applied Research Medal, and coworkers Hutchinson, Poliquit, Clulow, Gentle and Shaw contribute a research article on the detection of explosives containing nitro-groups by correlating vapour uptake with the luminescence quenching of poly(dendrimer)s. It was found that that the addition of first-generation biphenyl-based dendrons to one of the polymers resulted in improved photoluminescence quenching and sensitivity, whereby neutron reflectometry was applied to characterise vapour uptake. 4 Timothy U. Connell (Deakin University), the Organometallic Awardee, and Carol Hua (The University of Melbourne) contribute a research paper on control of the emission energy in metal organic frameworks combining calcium(II) with heteroleptic iridium(III) metalloligands containing 1,2-diimine ancillary ligands and different cyclometalated linkers.…”