16971-02-1Relevant academic research and scientific papers
Aggregation-Induced Emission Activity in Iridium(III) Diimine Complexes: Investigations of Their Vapochromic Properties
Alam, Parvej,Karanam, Maheswararao,Bandyopadhyay, Debashree,Choudhury, Angshuman Roy,Laskar, Inamur Rahaman
, p. 3710 - 3719 (2014)
Two iridium(III) diimine complexes [mono(1,10-phenanthroline)bis(triphenylphosphine)(dihydrido)iridium(III) hexafluorophosphate (1) and mono(1,10-phenanthroline)bis(triphenylphosphine)(hydrido)(chloro)iridium(III) hexafluorophosphate (2)] have been synthesized from a single two-step reaction. The structures of 1 and 2 both adopt distorted octahedral geometries, as established by single-crystal X-ray diffraction. The complexes, upon irradiation with UV light at 365 nm, emit faint light in solution and bright light in the solid state. The ground- and excited-state properties of these complexes were investigated through density functional theory (DFT) and time-dependent DFT calculations. The calculated energies for the transitions from the ground state to the singlet and triplet excited states were close to those determined from the experimental absorption and emission. Their molecular orbitals were also exploited to compute the ground-state dipole moments and redox potentials. Several experiments were performed to demonstrate the aggregation-induced emission (AIE) activity of these complexes. AIE was triggered by the restricted intramolecular rotation of the rotating units (phenyls in triphenyphosphines) in these molecules in the solid state. The solid thin films of 1 and 2 exhibit solvent-polarity-dependent vapour-responsive emission properties (vapoluminescent). The rationale for the different emission behavior in the solid state has been thoroughly investigated. The packing diagrams of 1 and 2 show that there is enough space available to accommodate small organic solvent molecules inside the crystal lattices.
Facile tuning of the aggregation-induced emission wavelength in a common framework of a cyclometalated iridium(III) complex: Micellar encapsulated probe in cellular imaging
Alam,Das,Climent,Karanam,Casanova,Choudhury,Alemany,Jana,Laskar
supporting information, p. 5615 - 5628 (2014/07/08)
A simple synthetic protocol involving two steps was developed for the syntheses of a series of monocyclometalated iridium(iii) complexes. Initially, an intermediate, [IrHCl[(o-C6H3X)P(Ar) x-(PArxRy)2] [A (i, j, k, l)], six-coordinated iridium(iii) complex involving a 4-membered chelate was isolated. Then, it was transformed into a monocyclometalated iridium(iii) complex, [(C^N)Ir(PArx-1Ry)2(Cl(H)] (1-12), by the replacement of the 4-membered chelates with 5-membered cyclometalates. The intermediates and the complexes were structurally characterized by FTIR, 1H, 13C and 31P NMR spectroscopies. Octahedral coordination for Ir(iii) in 2, 8 and 9 was established by single crystal X-ray diffraction. Photo-physical experiments and quantum chemical calculations revealed a mixed LC/MLCT/LLCT nature for the lowest excited states of all these complexes that emit bright light in the solid state. Fine tuning of the emission wavelength throughout the visible range was achieved by suitable combinations of chromophoric cyclometalates and non-chromophoric aryl phosphine ligands. More interestingly, all the studied complexes were found to be aggregation-induced emission (AIE) active. One of these AIE active materials (6) was encapsulated inside polymeric micelles that inhibit the macroscopic precipitation of the aggregated complex, a strong emission. These colloidal luminescent particles were used as a potential non-toxic bio-imaging probe. This journal is the Partner Organisations 2014.
