The synthesis, characterization and evaluation in solid-state devices of a series of 8 cationic iridium complexes bearing different numbers of methoxy groups on the cyclometallating ligands are reported. The optoelectronic characterization showed a dramatic red shift in the absorption and the emission and a reduction of the electrochemical gap of the complexes when a methoxy group was introduced para to the Ir-C bond. The addition of a second or third methoxy group did not lead to a significant further red shift in these spectra. Emission maxima over the series ranged from 595 to 730 nm. All complexes possessing a motif with a methoxy group at the 3-position of the cyclometalating ligands showed very short emission lifetimes and poor photoluminescence quantum yields whereas complexes having a methoxy group at the 4-position were slightly blue shifted compared to the unsubstituted parent complexes, resulting from the inductively electron withdrawing nature of this directing group on the Ir-C bond. Light-emitting electrochemical cells were fabricated and evaluated. These deep red emitters generally showed poor performance with electroluminescence mirroring photoluminescence. DFT calculations accurately modelled the observed photophysical and electrochemical behavior of the complexes and point to an emission from a mixed charge transfer state.

The structures and properties of six new iron(iii) diamine-bis(phenolate) complexes are reported. Reaction of anhydrous FeX(3) salts (where X = Cl or Br) with the diprotonated tripodal tetradentate ligands 2-pyridylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)[L(1)], and N,N-dimethyl-N',N'-bis(2-methylene-4-methyl-6-tert-butylphenol)ethylenediamine, H(2)[L(2)], produces the trigonal bipyramidal iron(iii) complexes, [L(1)]FeCl , [L(1)]FeBr , [L(2)]FeCl and [L(2)]FeBr . Reaction of FeX(3) with the related linear tetradentate ligand N,N'-bis(4,6-tert-butyl-2-methylphenol)-N,N'-bismethyl-1,2-diaminoethane, H(2)[L(3)], generates square pyramidal iron(iii) complexes, [L(3)]FeCl and [L(3)]FeBr . Complexes have been characterized using electronic absorption spectroscopy and magnetometry. Single crystal X-ray molecular structures have been determined for complexes 1, 3, 5 and 6.

Herein, we report the synthesis and electrochemical and spectroscopic characterization for a series of six bis(arylimino) acenaphthene, compounds commonly used as ligands in catalysis, polymerization and materials. Low energy absorption bands are the result of an intraligand charge transfer between the aryl groups and the acenaphthene core, and their energies obey a Hammett relationship with respect to substitution on the aryl.

We report the synthesis, X-ray structures, and optoelectronic characterization of two cationic iridium complexes bearing bis[(4-methoxyphenyl)imino]acenaphthene ligands. These complexes exhibited panchromic absorption extending as far as 800 nm, making them of interest for solar-energy-harvesting applications.

Four cationic iridium(III) complexes of the form [Ir(C^N)2(N^N)](+) bearing either a 2,5-dipyridylpyrazine (2,5-dpp) or a 2,2':5',2''-terpyridine (2,5-tpy) ancillary ligand and either 2-phenylpyridine (ppy) or a 2-(2,4-difluorophenyl)-5-methylpyridine (dFMeppy) cyclometalating ligands were synthesized. The optoelectronic properties of all complexes have been fully characterized by UV-visible absorption, cyclic voltammetry and emission spectroscopy. The conclusions drawn from these studies have been corroborated by DFT and TDDFT calculations. The four complexes were assessed as emitters in light-emitting electrochemical cells. Complex 1a, [Ir(ppy)2(2,5-dpp)]PF6, was found to be a deep red emitter (666 nm) both in acetonitrile solution and in the electroluminescent device. Complex 2a, [Ir(ppy)2(2,5-tpy)]PF6 was found to be an orange emitter (604 nm) both in solution and in the LEEC. LEECs incorporating both of these complexes were stable over the course of around 4-6 hours. Complex 1b, [Ir(dFMeppy)2(2,5-dpp)]PF6, was also determined to emit in the orange (605 nm) but with a photoluminescent quantum yield (ΦPL) double that of 2a. Complex 2b, [Ir(dFMeppy)2(2,5-tpy)]PF6 is an extremely bright green emitter (544 nm, 93%). All four complexes exhibited quasireversible electrochemistry and all four complexes phosphoresce from a mixed charge-transfer excited state.

Eight new iron(III) amine-bis(phenolate) complexes are reported. The reaction of anhydrous FeX(3) salts (where X = Cl or Br) with the diprotonated tripodal tetradentate ligands 2-tetrahydrofurfurylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L1, 2-tetrahydrofurfurylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)L2, and 2-methoxyethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L3, 2-methoxyethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)L4 produces the trigonal bipyramidal iron(III) complexes, L1FeCl (1a), L1FeBr (1b), L2FeCl (2a), L2FeBr (2b), L3FeCl (3a), L3FeBr (3b), L4FeCl (4a), and L4FeBr (4b). All complexes have been characterized using electronic absorption spectroscopy, cyclic voltammetry and room temperature magnetic measurements. Variable temperature magnetic data were acquired for complexes 2b, 3a and 4b. Variable temperature Mössbauer spectra were obtained for 2b, 3a and 4b. Single crystal X-ray molecular structures have been determined for proligand H(2)L4 and complexes 1b, 2b, and 4b.

A new class of cationic iridium(III) complexes of the form [(C(∧)N)2Ir(N(∧)N)][PF6] is reported, where C(∧)N = cyclometallating 2-phenylpyridinato, ppy, or 2-(2,4-difluorophenyl)-5'-methylpyridinato, dFMeppy, and N(∧)N = guanidyl-pyridine, gpy, or -pyrazine, gpz, as the ancillary ligand. A large blue-shift in the emission coupled with a 7-to-9 fold enhancement in photoluminescence quantum yield and microsecond emission lifetimes were observed for the complexes containing the partially saturated gpy ligand as compared to the benchmark complex [(ppy)2Ir(bpy)][PF6], C1, where bpy is 2,2'-bipyridine.

Developing heterogeneous catalyst using chitosan (CS) and magnetic Fe3O4 as support has been remarkably attractive due to their availability, low cost and non-toxicity. In this work, a heterogeneous catalyst (denoted as Fe3O4@CS@MS@Ag) was fabricated by the deposition of silver nanoparticles on magnetic chitosan via an easy and facile modification of its surface with methyl salicylate (MS). The catalyst was characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). To the best of our knowledge, for the first time, CS decorated Fe3O4 (Fe3O4@CS) has shown the catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in presence of NaBH4. Surface modified magnetic chitosan (Fe3O4@CS@MS) also acts as active catalyst towards the reduction of 4-NP. However, catalytic efficiency has increased fourfold when silver-nanoparticles-deposited magnetic chitosan (Fe3O4@CS@MS@Ag) used as our target catalyst. The catalyst was separated with external magnet after each cycle of catalytic reaction and reused effectively five times with almost 90% efficiency.