Abstract
A mechanochemical method is reported for the synthesis of Au(diphos)X complexes of diphosphine (diphos = XantPhos and N-XantPhos) ligands and halide ions (X = Cl and I). The Au(XantPhos)X (1: X = Cl; 2: X = I) and Au(N-XantPhos)Cl (3) complexes exhibited either yellowish green (1) or bluish green (2) emission, whereas 3 was seemingly non-emissive in the solid state at room temperature. Blue- (2B) and bluish green (2G) luminescent concomitant solvates of 2 were obtained by recrystallization. Luminescent colour changes from blue (2B) or bluish green (2G) to yellow were observed when these forms were subjected to mechanical stimulus, while the original emission colour can be recovered in the presence of solvent vapours. Moreover, the luminescence of 2B can be reversibly altered between blue and yellow by heating/cooling-cycles. These results demonstrate the power of mechanochemistry in the rapid (4 min reaction time), efficient (up to 98% yield) and greener synthesis of luminescent and stimuli-responsive gold(I) complexes.
Highlights
A mechanochemical method is reported for the synthesis of Au(diphos)X complexes of diphosphine ligands and halide ions (X = Cl and I)
The luminescence of 2B can be reversibly altered between blue and yellow by heating/cooling-cycles. These results demonstrate the power of mechanochemistry in the rapid (4 min reaction time), efficient and greener synthesis of luminescent and stimuli-responsive gold(I) complexes
Even though the yields obtained from the solution synthesis (87% for both complexes 1 and 2 and 98% for complex 3) were comparable with those obtained by mechanochemistry (94%, 90% and 98% respectively for complexes 1–3, see Electronic supplementary information (ESI), Table S1†) the reaction time (4 minutes) needed for the mechanochemical synthesis of complexes 1–3 was significantly
Summary
Molecular functional materials based on gold(I) complexes have gained increasing attention for their numerous promising applications in new optoelectronic devices,[1,2,3] sensing,[4,5]phosphines have been used in the preparation of electroluminescent (LED) devices,[22,23,24] for biochemical[25] and biomedical applications[26,27] and for bioimaging.[28]the increasing demand for clean processes and ecoconscious reaction conditions has fostered the application of mechanochemistry in organic[29,30] and organometallic syntheses,[31] in metal catalysis,[32] for the preparation of co-crystals,[33] metal clusters,[34,35,36] metal–organic frameworks (MOFs)[37] and coordination polymers (CPs),[38,39] pharmaceutical materials[40,41,42] and ingredients (APIs and metallo-drugs).[43,44,45]In the last few decades, this technology has provided access to an impressive number of discrete metal complexes,[31,46,47] as well as infinite CPs48,49 and MOFs,[49] in a rapid and environmentally-sustainable fashion. The experimental PXRD patterns of mechanochemically prepared bluish green-emitting 2 resemble with the simulated patterns derived from the single crystal data of 2G form (see ESI, Fig. S17†), there are additional reflections present only in the diffractogram of 2.
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