The sequential reaction of a multisite coordinating compartmental ligand [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] (LH4 ) with appropriate lanthanide salts followed by the addition of [Mg(NO3 )2 ]⋅6 H2 O or [Zn(NO3 )2 ]⋅6 H2 O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2 Ln](3+) (Ln=Dy, Gd, and Tb) and [Zn2 Ln](3+) (Ln=Dy, Gd, and Tb) cores. The formation of these complexes is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. The comprehensive studies discussed involve the synthesis, structure, magnetism, and photophysical properties on this family of trinuclear [Mg2 Ln](3+) and [Zn2 Ln](3+) heterometallic complexes. [Mg2 Dy](3+) and [Zn2 Dy](3+) show slow relaxation of the magnetization below 12 K under zero applied direct current (dc) field, but without reaching a neat maximum, which is due to the overlapping with a faster quantum tunneling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied dc field of 1000 Oe, the quantum tunneling is almost suppressed and temperature and frequency dependent peaks are observed, thus confirming the single-molecule magnet behavior of complexes [Mg2 Dy](3+) and [Zn2 Dy](3+) .

†Electronic Supplementary Information (ESI) available: X-ray crystallographic data in CIF format for the complexes Ir2 and Ir4 [CCDC 973778 (Ir2) and 1005716 (Ir4)], NMR and MASS spectra of ligands and complexes, TGA−DSC thermal curves, cyclic voltammograms, lifetime curves, selected bond lengths and angles, intermolecular interactions, calculated transitions of Ir1-Ir5 in CH2Cl2 media and composition of the MOs and the assignment of different fragments. CIF files. See Herein, we have synthesized a series of 2',6'-difluoro-2,3'-bipyridine cyclometalating ligands by substituting electronwithdrawing (-CHO, -CF3, -CN) and electron-donating (-OMe, -NMe2) groups at the 4′ posiƟon of the pyridyl moiety and utilized for the construction of five new iridium(III) complexes (Ir1-Ir5) in the presence of picolinate as an ancillary ligand. The photophysical properties of the developed iridium(III) compounds were investigated with a view to understand the substituent effects. The strong electron-withdrawing (-CN) group containing iridium(III) compound (Ir3) exhibits highly efficient genuine green phosphorescence (λmax= 508 nm) at room temperature in solution and in thin film, with an excellent quantum efficiency (ΦPL) of 0.90 and 0.98, respectively. On the other hand, the -CF3 group substituted iridium(III) compound (Ir2) displays a sky-blue emission (λmax = 468 nm) with a promising quantum efficiency (ΦPL = 0.88 and 0.84 in solution and in thin film, respectively). The -CHO substituted iridium(III) complex (Ir1) showed greenishyellow emission (λmax = 542 nm). Most importantly, the strong electron-donating -NMe2 substituted iridium(III) complex (Ir5) gives a structureless and a broad emission profile in the wavelength region 450 to 700 nm (λmax = 520 nm) with a poor quantum efficiency. An intense blue phosphorescence with impressive quantum efficiency, especially in thin-film noted in the case of -OMe substituted iridium(III) complex (Ir4). Comprehensive density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches have been performed on the ground and excited states of the synthesized iridium(III) complexes, in order to obtain information about the absorption and emission processes and to gain deeper insights into the photophysical properties. The combinations of a smaller ΔES1-T1 and higher contribution of 3 MLCT in the emission process result in the higher quantum yields and lifetime values for complexes Ir1-Ir3. Multi-layered Phosphorescence Organic Light Emitting Diodes (PhOLEDS) were designed using the phosphorescent dopants Ir2, Ir3 and Ir4 and evaluated their elecroluminescence properties. The compound Ir4 at a doping level of 5 wt% shows the best performance with an external quantum efficiency of 4.7% , in nonoptimized device, and power efficiency of 5.8 lm W −1 , together with a true-blue chromacity CIEx,y = 0.15, 0.17 recorded at maximum brightness of 33,180 cd/m 2 . 28,[45][46][47][48][49][50][51] Accordingly, several groups have demonstrated that phosphorescence emission wavelengths can be tuned in t...

Detection of explosives, especially trinitrotoluene (TNT), is of utmost importance due to its highly explosive nature and environmental hazard. Therefore, detection of TNT has been a matter of great concern to the scientific community worldwide. Herein, a new aggregation-induced phosphorescent emission (AIPE)active iridium(III) bis(2-(2,4-difluorophenyl)pyridinato-N,C2 0 ) (2-(2-pyridyl)benzimidazolato-N,N 0 ) complex [FIrPyBiz] has been developed and serves as a molecular probe for the detection of TNT in the vapor phase, solid phase, and aqueous media. In addition, phosphorescent test strips have been constructed by impregnating Whatman filter paper with aggregates of FIrPyBiz for trace detection of TNT in contact mode, with detection limits in nanograms, by taking advantage of the excited state interaction of AIPEactive phosphorescent iridium(III) complex with that of TNT and the associated photophysical properties.

AIPE active deep-red and near infrared iridium(iii) complexes were developed using electron withdrawing substituents and effectively utilized them in solution processable PhOLEDs.

Two different kinds of ancillary ligands such as picolinate and thenoyltrifluoroacetylacetonate have profound effects on the excited state properties of deep red emissive iridium(iii) complexes

Substituent effects on the photophysics of deep-red to near-infrared emissive iridium(iii) complexes.

The sequential reaction of 2-((6-(hydroxymethyl)pyridin-2-yl)-methyleneamino)phenol (LH), LnCl·6HO, and 1,1,1-trifluoroacetylacetone (Htfa) in the presence of EtN afforded [Ln(LH) (tfa)] [Ln = Dy (1), Ln = Tb (2), and Ln = Gd (3)], while under the same reaction conditions, but in the absence of the coligand, another series of mononuclear complexes, namely, [Ln(LH)]·Cl·2MeOH] [Ln = Dy (4) and Tb (5)] are obtained. Single-crystal X-ray diffraction analysis revealed that the former set contains a mono-deprotonated [LH] and two tfa ligands, while the latter set comprises of two mono-deprotonated [LH] ligands that are nearly perpendicular to each other at an angle of 86.9°. Among these complexes, 2 exhibited a ligand-sensitized lanthanide-characteristic emission. Analyses of the alternating current susceptibility measurements reveal the presence of single-molecule magnet behavior for 1 and 4, in the presence of direct-current field, with effective energy barriers of 4.6 and 44.4 K, respectively. The enhancement of the effective energy barrier of the latter can be attributed to the presence of a large energy gap between the ground and first excited Kramers doublets, triggered by the change in coordination environments around the lanthanide centers.

A new phosphorescent iridium(III) complex, bis[2',6'-difluorophenyl-4-formylpyridinato-N,C4']iridium(III) (picolinate) (IrC), was synthesized, fully characterized by various spectroscopic techniques, and utilized for the detection of CN(-) on the basis of the widely known hypothesis of the formation of cyanohydrins. The solid-state structure of the developed IrC was authenticated by single-crystal X-ray diffraction. Notably, the iridium(III) complex exhibits intense red phosphorescence in the solid state at 298 K (ΦPL = 0.16) and faint emission in acetonitrile solution (ΦPL = 0.02). The cyanide anion binding properties with IrC in pure and aqueous acetonitrile solutions were systematically investigated using two different channels: i.e., by means of UV-vis absorption and photoluminescence. The addition of 2.0 equiv of cyanide to a solution of the iridium(III) complex in acetonitrile (c = 20 μM) visibly changes the color from orange to yellow. On the other hand, the PL intensity of IrC at 480 nm was dramatically enhanced ∼5.36 × 10(2)-fold within 100 s along with a strong signature of a blue shift of the emission by ∼155 nm with a detection limit of 2.16 × 10(-8) M. The cyanohydrin formation mechanism is further supported by results of a (1)H NMR titration of IrC with CN(-). As an integral part of this work, phosphorescent test strips have been constructed by impregnating Whatman filter paper with IrC for the trace detection of CN(-) in the contact mode, exhibiting a detection limit at the nanogram level (∼265 ng/mL). Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed to understand the electronic structure and the corresponding transitions involved in the designed phosphorescent iridium(III) complex probe and its cyanide adduct.