Photocatalytic reduction of carbon dioxide by BiTeX (X = Cl, Br, I) under visible-light irradiation.

In this study, a series of BiTeX (X = Cl, Br, I) photocatalysts were successfully synthesized via a simple hydrothermal method. The synthesis process involved dissolving BiX3 and Te powder in toluene to identify the most efficient material for photocatalytic activity. The main objective of this approach is to facilitate the conversion of carbon dioxide into sustainable solar fuels, such as alcohols and hydrocarbons, offering an appealing solution to address environmental concerns and energy crises. The BiTeX photocatalysts demonstrated significant proficiency in converting CO2 into CH4, particularly BiTeCl exhibited a notable photocatalytic conversion rate of up to 0.51 µmolg-1h-1. The optimized BiTeX photocatalysts displayed a gradual and selective transition from CO2 to CH4, ultimately producing valuable hydrocarbons (C2+). Furthermore, owing to their ability to reduce CO2, these photocatalysts show promise as materials for mitigating environmental pollution.

Experimental Revelation of Surface and Bulk Lattices in Faceted Cu2 O Crystals.

Semiconductor crystals have generally shown facet-dependent electrical, photocatalytic, and optical properties. These phenomena have been proposed to result from the presence of a surface layer with bond-level deviations. To provide experimental evidence of this structural feature, synchrotron X-ray sources are used to obtain X-ray diffraction (XRD) patterns of polyhedral cuprous oxide crystals. Cu2 O rhombic dodecahedra display two distinct cell constants from peak splitting. Peak disappearance during slow Cu2 O reduction to Cu with ammonia borane differentiates bulk and surface layer lattices. Cubes and octahedra also show two peak components, while diffraction peaks of cuboctahedra are comprised of three components. Temperature-varying lattice changes in the bulk and surface regions also show shape dependence. From transmission electron microscopy (TEM) images, slight plane spacing deviations in surface and inner crystal regions are measured. Image processing provides visualization of the surface layer with depths of about 1.5-4 nm giving dashed lattice points instead of dots from atomic position deviations. Close TEM examination reveals considerable variation in lattice spot size and shape for different particle morphologies, explaining why facet-dependent properties are emerged. Raman spectrum reflects the large bulk and surface lattice difference in rhombic dodecahedra. Surface lattice difference can change the particle bandgap.

In situ and real-time vibrational spectroscopic characterizations of the photodegradation of nitrite in the presence of methanediol.

Nitrite (NO2-) is one of the common salts in aqueous aerosols, and its photolytic products, nitric oxide (NO) and hydroxyl radical (OH), have potential for use in the oxidation of organic matter, such as dissolved formaldehyde, methanediol (CH2(OH)2), which is regarded as the precursor of atmospheric formic acid. In this work, the simulation of UVA irradiation in an aqueous mixture of NaNO2/CH2(OH)2 was carried out via continuous exposure with a 365 nm LED lamp, and the reaction evolutions were probed by in situ and real-time infrared and Raman spectroscopy, which provided multiplexity in the identification of the relevant species and the corresponding reaction evolution. Although performing infrared absorption measurements in aqueous solution seemed impracticable due to the strong interference of water, the multiplexity of the vibrational bands of parents and products in the non-interfered infrared regimes and the conjunction with Raman spectroscopy still make it possible to perform in situ and real-time characterization of the photolytic reaction in the aqueous phase, supplementary to chromatographic approaches. During the 365 nm irradiation, NO2- and CH2(OH)2 gradually decreased, concomitant with the formation of nitrous oxide (N2O) and formate (HCOO-) in the early period and carbonate (CO32-) in the late period, as revealed by the vibrational spectra. The losses or the gains of the aforementioned species increased with increases in the concentration of CH2(OH)2 and the irradiation flux of the 365 nm UV light. The ionic product HCOO- was also confirmed by ion chromatography, but oxalate (C2O42-) was absent in the vibrational spectra and ion chromatogram. The reaction mechanism is reasonably proposed on the basis of the evolutions of the aforementioned species and the predicted thermodynamic favorableness.

S- Cis Diene Conformation: A New Bathochromic Shift Strategy for Near-Infrared Fluorescence Switchable Dye and the Imaging Applications.

In this paper, we present a novel charge-free fluorescence-switchable near-infrared (IR) dye based on merocyanine for target specific imaging. In contrast to the typical bathochromic shift approach by extending π-conjugation, the bathochromic shift of our merocyanine dye to the near-IR region is due to an unusual S- cis diene conformer. This is the first example where a fluorescent dye adopts the stable S- cis conformation. In addition to the novel bathochromic shift mechanism, the dye exhibits fluorescence-switchable properties in response to polarity and viscosity. By incorporating a protein-specific ligand to the dye, the probes (for SNAP-tag and hCAII proteins) exhibited dramatic fluorescence increase (up to 300-fold) upon binding with its target protein. The large fluorescence enhancement, near-IR absorption/emission, and charge-free scaffold enabled no-wash and site-specific imaging of target proteins in living cells and in vivo with minimum background fluorescence. We believe that our unconventional approach for a near-IR dye with the S- cis diene conformation can lead to new strategies for the design of near-IR dyes.

Temperature-Controlled Thiation of α-Cyano-ß-Alkynyl Carbonyl Derivatives for De Novo Synthesis of 2-Aminothiophenes and Thieno[2,3- c]isothiazoles.

Making use of temperature-controlled thiation as a key operation, a simple route to 2-aminothiophenes or thieno[2,3- c]isothiazoles has been newly developed wherein the 2-aminothiophene nucleus was formed through an initial formation of thioamide followed by a 5-exo-dig addition to the tethered alkyne; however, under harsher thermal conditions, excess sulfur-transferring reagents enabled further oxidative thiation to generate the corresponding thieno[2,3- c]isothiazoles.

Isomerization Reaction of mer- to fac-Tris(2-phenylpyridinato-N,C2')Iridium(III) Monitored by Using Surface-Enhanced Raman Spectroscopy.

We developed a new method by enclosing the complex tris(2-phenylpyridinato-N,C2')Iridium(III), Ir(ppy)3 with surfactant cetyltrimethylammonium bromide (CATB), coated with a thin layer of silica then bonded to the surface of silver nanoparticle. These samples were used to acquire surface-enhanced Raman scattering (SERS) spectra. The thickness of silica layer was controlled to have efficient phosphorescence quenching and Raman enhancement by metal nanoparticle. The SERS spectra of fac- and mer-Ir(ppy)3, recorded at 633 nm excitation, display distinct ring breathing mode features because the total symmetric vibrational bands were enhanced. This provides a convenient means to differentiate these isomers with great sensitivity and to study their isomerization process. A direct conversion reaction of mer- to fac- isomerization is identified with time constant 3.1 min when mer was irradiated with Xe light. Via thermal activation, under moderate conditions (pH 5.5 and 343 K), we observed an intermediate particularly with new bands 320/662 cm-1 after heating for 17.5 h, and then those bands disappeared to form fac-Ir(ppy)3. On the basis of DFT calculations, the intermediate is proposed to contain octahedral N-N Ir(ppy)3-HO-silica structure; band at 320 cm-1 is assigned to iridium oxygen stretching mode νIr-O of this intermediate. Under acidic conditions, pH 1-2 catalyzed by silanol in silica, byproduct with band at 353 cm-1 was observed. According to the SERS bands and the calculation, this byproduct is assigned to be iridium(III) siloxide, and the new band is assigned to νIr-O.

Ligand-Unsupported Cuprophilicity in the Preparation of Dodecacopper(I) Complexes and Raman Studies.

Synthesis and characterization of two dodecacopper(I) extended metal atom chains (EMAC) assembled by two hexadentate bis(pyridylamido)amidinate-supported hexacopper(I) string complexes (monomers) via the ligand-unsupported cuprophilicity are described. In addition to short unsupported Cu-Cu contacts, two hexacopper fragments in these two dodecacopper EMACs show a bent conformation based on X-ray crystallography. Compared with their THF-bound hexacopper(I) monomers and protonated ligands, these ligand-unsupported cuprophilic interactions are shown to be weak by Raman spectroscopy. DFT calculations suggest the ligand-unsupported cuprophilicity originate from weak attractive orbital interactions, and the strength is estimated to be 2.4 kcal mol-1 .

Excited state dynamics of symmetric and asymmetric Cr3(dpa)4Cl2 measured using femtosecond transient absorption spectroscopy.

Herein, the excited-state dynamics of an extended metal atom chain complex, Cr3(dpa)4Cl2 (dpa = dipyridylamide), in tetrahydrofuran solution were investigated using femtosecond transient absorption spectroscopy. Upon excitation at a wavelength of 330 nm, two distinct excited-state absorption species with varied dynamics were identified and assigned to the symmetric (s-) and unsymmetric (u-) Cr3(dpa)4Cl2. The major species is s-Cr3(dpa)4Cl2 that undergoes rapid conversion at less than 100 fs from the ligand-centred π-π* state, which is the initially accessed state, to the metal-centred d-d state and then vibrational cooling accompanying the structural relaxation at a time constant ∼2.2 ps. Most of the s-form is recovered to the ground state at ∼200 ps. For u-Cr3(dpa)4Cl2, a similar rapid conversion to d-d states is observed, and the geometric/vibrational relaxation is ∼0.8 ps. The second recovery of the ground state with approximately equal amplitude is observed at a time constant of ∼5 ns. This might be because many d-d states exist and about half of them inefficiently couple with the ground state surface.

Charge and Energy Transfer Dynamics in Dimethylsilylene-Spaced Aminostyrene Stilbene Monomer Using Time-Resolved Techniques.

We used transient absorption and time-correlated single photon counting (TCSPC) techniques to investigate the charge transfer reaction in monosilylene-spaced aminostyrene stilbene monomer. With 266 nm excitation, both stilbene (sti) and aminostyrene (ast) moieties were excited. In nonpolar solvents, the transient absorption band centered at 600 nm appeared promptly and is assigned to the excited state of sti*; this state relaxes at time constant 1.2-1.4 ps and is explained to proceed energy transfer to ast 1ππ*. The second transient band at 460 nm is assigned to absorption of ast 2ππ*; this state accessed from direct excitation has a lifetime 65 ps. This agrees with the observation of 85-89 ps emission decay from the TCSPC measurements. In polar solvent, an excited absorption band centered at 530 nm appeared with a rise time constant 0.2-0.6 ps. This band is assigned to the charge transfer state. This charge transfer process occurs as the acceptor fluorophore (sti) is excited and the electron moves from the occupied π orbital of donor ast to sti* forming ast+sti-. This rise time corresponds to the combined processes of charge and energy transfers. The second rise in this charge-transfer state at time constant 0.74-1.5 ps is observed and assigned to occur from electron hopping from ast 2π* orbital to sti π*. The third time constant 18-31 ps is observed and is attributed to conversion of anti to syn form in the charge-transfer state because the syn form is more polar and further stabilized in polar environment. A rapid charge transfer process in monosilylene-spaced system although two Si-C single bonds are used as spacer is possibly because of the short distance of the ast and the sti conjugated systems, resulting in π orbital overlap between donor and acceptor.

Charge-transfer and isomerization reactions of trans-4-(N-arylamino)stilbenes.

We studied the excited-state dynamics of trans-4-(N-arylamino)stilbenes with aryl = phenyl (p1H), 4-methoxyphenyl (p1OM), or 4-cyanophenyl (p1CN) in solvents of varied polarity and viscosity by using femtosecond transient absorption and time-correlated single photon counting techniques. In nonpolar solvents the decay is triexponential, in which the rapid component corresponds to vibrational cooling combined with solvation, the intermediate temporal component 41-120 ps to trans-cis isomerization, and the long one ∼1 ns to fluorescence decay of the S1 state. The S1 state has a delocalized geometry and charge-transfer characteristics, corresponding to a planar intramolecular charge transfer (PICT) state. In polar solvents, an excited-state absorption band appears near 520 and 480 nm for p1OM and p1CN, respectively but not for p1H. This band has a rise lifetime of 4.3/7.5, 16.3/9.4, and 29.5/16 ps for p1CN/p1OM in acetonitrile (ACN), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), respectively and matches the decay of the 600 nm PICT band. This band is thus assigned to the absorption of a singlet twisted intramolecular charge transfer state (TICT). The conversion rate decreases as the solvent viscosity is increased and is consistent with a large structural variation amplitude. Theoretical calculations using density functional theory (DFT), method PEB0, were employed to obtain the optimized structures and energies of those states. The PICT state possesses delocalized π electrons along the molecule. The TICT for p1CN is formed by twisting about the aminostilbene-benzonitrile C-N bond by ∼90°, but it is about the stilbene-aniline C-N bond for p1OM. We observed faster conversion rates for p1CN in alcoholic solvents, in which the lifetimes for both the PICT and TICT states are shortened to 20-99 ps and 120-660 ps, respectively, as a result of solvent-solute H-bonding interactions. In p1OM, the TICT state has an elongated C[double bond, length as m-dash]C bond in the stilbene moiety, which might facilitate the trans-cis isomerization reaction and thus account for the relatively short lifetime of 58-420 ps in polar solvents.

Synthesis and Structure-Activity Relationships of Imidazole-Coumarin Conjugates against Hepatitis C Virus.

A series of new conjugated compounds with a -SCH2- linkage were synthesized by chemical methods from imidazole and coumarin derivatives. The experimental results indicate that of the twenty newly synthesized imidazole-coumarin conjugates, three of them exhibited appealing EC50 values (5.1-8.4 µM) and selective indices >20 against hepatitis C virus. Their potency and selectivity were increased substantially by modification of their structure with two factors: imidazole nucleus with a hydrogen atom at the N(1) position and coumarin nucleus with a substituent, such as Cl, F, Br, Me, and OMe. These guidelines provide valuable information for further development of conjugated compounds as anti-viral agents.

The first heteropentanuclear extended metal-atom chain: [Ni⁺-Ru25⁺-Ni²âº-Ni²âº (tripyridyldiamido)4(NCS)2].

This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru2(5+) unit. This [Ru2]-containing EMAC exhibits single-molecule conductance four-fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium-modulated EMAC.

Investigation of Electronic Structures of Triplet States Using Step-Scan Time-Resolved Fourier-Transform Near-Infrared Spectroscopy.

Triplet transitions of light-emitting materials, including rose bengal, tris(2-phenylpyridine)iridium(III) [Ir(ppy)3], tris(1-phenylisoquinoline)iridium(III) [Ir(piq)3], and bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic), were studied using step-scan time-resolved Fourier-transform near-infrared spectroscopy. The samples were excited to their singlet excited states by a 355 nm laser and then underwent efficient conversions/crossings to their triplet manifolds. For rose bengal, a transient absorption band appeared at 9400 cm-1, attributed to the T3 ← T1 transition based on the corresponding time evolution and the theoretical calculations. For Ir(ppy)3, Ir(piq)3, and FIrpic, the most intense bands were observed at 7700, 7500, and 7500 cm-1 and assigned to T7 ← T1, T6 ← T1, and T6 ← T1 transitions, respectively. For Ir(ppy)3, the most intense band involved transitions between different triplet metal-to-ligand charge transfer (3MLCT) states, while for Ir(piq)3 and FIrpic, they involved a metal center to 3MLCT transition. These T1 states were assigned to 3MLCT.

Controlling conformations in alternating dialkylsilylene-spaced donor-acceptor copolymers by a cooperative Thorpe-Ingold effect and polymer folding.

A series of dialkylsilylene-spaced copolymers 6 and 7, which contain Me(2)Si and iPr(2)Si spacer groups, respectively, and have alternating donor and acceptor chromophores, have been designed and regioselectively synthesized by hydrosilylation. The ratio of the donor and acceptor chromophores for each repeat unit is 2:1, and the two donor chromophores are linked by a trimethylene bridge. A 4-aminostyrene moiety is used as the donor and a series of acceptor chromophores with different reduction potentials are employed. Both steady-state and kinetic measurements reveal that the photoinduced electron transfer (PET) in 6 obeyed the Marcus theory in which normal and inverted regions are observed. On the other hand, the iPr(2)Si-spaced copolymers 7 exhibit absorption and emission from the charge-transfer complexes exclusively due to ground-state interactions between the donor and acceptor chromophores. The discrepancy in photophysical behavior may have arisen from the difference in distance between the adjacent donor and acceptor chromophores. The bulkiness of the substituents on the silicon atom (i.e., Me versus iPr) may exert the Thorpe-Ingold effect on the local conformation around the silicon atom. The differences in the small energetic barriers for each of the conformational states may be amplified by extending the distance of the folding structure, which results in perturbing the conformation of the polymers. These results suggest that the electronic interactions between adjacent donor-acceptor pairs in these copolymers are controlled by the synchronization of the substitution effect and corresponding polymeric structures.

Design and synthesis of iridium bis(carbene) complexes for efficient blue electrophosphorescence.

Five iridium bis(carbene) complexes, [Ir(pmi)(2)(pypz)] (1), [Ir(mpmi)(2)(pypz)] (2), [Ir(fpmi)(2)(pypz)] (3), [Ir(fpmi)(2)(pyim)] (4), and [Ir(fpmi)(2)(tfpypz)] (5) (pmi=1-phenyl-3-methylimdazolin-2-ylidene-C,C(2'); fpmi=1-(4-fluorophenyl)-3-methylimdazolin-2-ylidene-C,C(2'); mpmi=1-(4-methyl-phenyl)-3-methylimdazolin-2-ylidene-C,C(2'); pypz=2-(1H-pyrazol-5-yl)pyridinato; pyim=2-(1H-imidazol-2-yl)pyridinato; and tfpypz=2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridinato), were synthesized and their structures were characterized by NMR spectroscopy, mass spectroscopy and X-ray diffraction. These complexes showed phosphorescent emission with the emission maxima between 453 and 490 nm. Various spectrophotometric measurements, cyclic voltammetric studies, and density functional theory (DFT) calculations show that, unlike most of the phosphorescent cyclometalated iridium complexes, the lowest unoccupied molecular orbital (LUMO) energy and the emissive state of these iridium complexes are mainly controlled by the N,N'-heteroaromatic (N^N) ligand. Despite the fact that the LUMO levels of these complexes are mainly on the N^N ligands, the efficiencies of the electroluminescent (EL) devices are very high. For example, the EL devices using [Ir(mpmi)(2)(pypz)], [Ir(fpmi)(2)(pypz)], and [Ir(fpmi)(2)(tfpypz)] as the dopant emitters exhibited light- to deep-blue electrophosphorescence with external quantum efficiencies of 15.2, 14.1, and 7.6% and Commission Internationale d'Énclairage (x,y) coordinates (CIE(x,y)) of (0.14, 0.27), (0.14, 0.18) and (0.14, 0.10), respectively.

Discrimination of mononuclear and dinuclear dinitrosyl iron complexes (DNICs) by S K-edge X-ray absorption spectroscopy: insight into the electronic structure and reactivity of DNICs.

In addition to probing the formation of dinitrosyl iron complexes (DNICs) by the characteristic Fe K-edge pre-edge absorption energy ranging from 7113.4 to 7113.8 eV, the distinct S K-edge pre-edge absorption energy and pattern can serve as an efficient tool to unambiguously characterize and discriminate mononuclear DNICs and dinuclear DNICs containing bridged-thiolate and bridged-sulfide ligands. The higher Fe-S bond covalency modulated by the stronger electron-donating thiolates promotes the Fe → NO π-electron back-donation to strengthen the Fe-NO bond and weaken the NO-release ability of the mononuclear DNICs, which is supported by the Raman ν(Fe-NO) stretching frequency. The Fe-S bond covalency of DNICs further rationalizes the binding preference of the {Fe(NO)(2)} motif toward thiolates following the trend of [SEt](-) > [SPh](-) > [SC(7)H(4)SN](-). The relative d-manifold energy derived from S K-edge XAS as well as the Fe K-edge pre-edge energy reveals that the electronic structure of the {Fe(NO)(2)}(9) core of the mononuclear DNICs [(NO)(2)Fe(SR)(2)](-) is best described as {Fe(III)(NO(-))(2)}(9) compared to [{Fe(III)(NO(-))(2)}(9)-{Fe(III)(NO(-))(2)}(9)] for the dinuclear DNICs [Fe(2)(µ-SEt)(µ-S)(NO)(4)](-) and [Fe(2)(µ-S)(2)(NO)(4)](2-).

A comparative study of gold nanocubes, octahedra, and rhombic dodecahedra as highly sensitive SERS substrates.

Gold nanocubes, octahedra, and rhombic dodecahedra with roughly two sets of particle sizes have been successfully synthesized via a seed-mediated growth approach. All six samples were analyzed for comparative surface-enhanced Raman scattering (SERS) activity. All of these Au nanostructures were found to yield strong enhancement at a thiophenol concentration of 10(-7) M and are excellent SERS substrates. Rhombic dodecahedra with a rhombus edge length of 32 nm showed significantly better enhancement than the other samples and can reach a detection limit of 10(-8) M. Simulations of the binding energies of thiophenol on the different faces of gold and electric near-field intensities of these nanocrystals have been performed to evaluate the experimental results. Superior SERS activity of these nanocrystals can be expected toward the detection of many other molecules.

Excited-state dynamics of the metal string complex Co3(dpa)4(NCS)2 from femtosecond transient absorption spectra.

Transient absorption spectroscopy is used to study the excited-state dynamics of Co(3)(dpa)(4)(NCS)(2), where dpa is the ligand di(2-pyridyl)amido. The pi pi*, charge-transfer, and d-d transition states are excited upon irradiation at wavelengths of 330, 400 and 600 nm, respectively. Similar transient spectra are observed under the experimental temporal resolution and the transient species show weak absorption. We thus propose that a low-lying metal-centered d-d state is accessed immediately after excitation. Analyses of the experimental kinetic traces reveal rapid conversion from the ligand-centered pi pi* and the charge-transfer states to this metal-centered d-d state within 100 fs. The excited molecule then crosses to a second d-d state within the ligand-field manifold, with a time coefficient of 0.6-1.4 ps. Because the ground-state bleaching band recovers with a time coefficient of 10-23 ps, we propose that an excited molecule crosses from the low-lying d-d state either directly within the same spin system or with spin crossing via the state (2)B to the ground state (2)A(2) (symmetry group C(4)). In this trimetal string complex, relaxation to the ground electronic surface after excitation is thus rapid.

Excited-state dynamics of metal string complex Ni3(dpa)4X2 from femtosecond transient absorption spectra.

The excited-state dynamics of Ni(3)(dpa)(4)X(2), in which dpa is the ligand di(2-pyridyl)amido and X = NCS or Cl, are investigated by transient absorption spectroscopy. The pi pi* and dd states are excited upon irradiation at wavelengths of 330 and 600 nm, respectively. Similar transient spectra are observed under the experimental temporal resolution. The transient species also show weak absorption. It is proposed that a low-lying metal-centered dd state is accessed immediately after excitation. Analyses of the experimental kinetic traces reveal a rapid conversion from a ligand-centered pi pi* state to a metal-centered dd state in 0.1-0.4 ps. Vibrational cooling occurs with a time coefficient of 3.0-15.9 ps. From the spectral shift observed in the transient spectra relative to the steady-state spectra, the dd state is assigned as B(1)/B(2)(Ni(t)). This dd state eventually converts to the electronic ground state, in about 100 ps for the isothiocyanate complex and 200 ps for the chloride. In this trimetal string complex, relaxation to the ground electronic surface after excitation is therefore rapid.

Dynamics of the excited states of [Ir(ppy)2bpy]+ with triple phosphorescence.

We investigated the relaxation dynamics of bis(2-phenylpyridinato-)(2,2'-bipyridine)iridium(III), [Ir(ppy)(2)bpy](+) using the technique of time-resolved spectroscopy. In the visible emission spectra this molecule exhibits triple phosphorescence: displaying blue, green, and orange bands. From the dependence of spectral shifts with polarity of solvent, decay lifetimes, and the results of calculations using time-dependent density functional theory, we assigned these three emitting states to be triplet interligand charge-transfer ((3)LLCT), metal-to-ligand ppy charge transfer ((3)MLCT(ppy)), and metal-to-ligand bpy charge transfer ((3)MLCT(bpy)) states. The blue states were formed promptly after excitation at wavelength 355 nm; the one lying at higher energy decaying with a time coefficient 0.79-2.56 ns is assigned to be a triplet MLCT, and the other at lower energy decaying in 1.5-2.8 µs is assigned to (3)LLCT(A), A symmetry. This decay time coefficient of (3)LLCT(A) decreases with increasing dielectric constant of the solvent indicating this state mixing of some MLCT character. The green state (3)MLCT(ppy) decays in 0.13-4.8 ns to a nearby intermediate state either (3)MLCT(ppy) or (3)MLCT(bpy). The orange state (3)MLCT(bpy) is coupled to the intermediate state to have a rise time about 0.36-0.84 ns and decays in 425-617 ns. Although many triplet states exist in a small energy range, they couple weakly to display triple emission. All (3)LLCT and (3)MCLT states are coupled to the singlet (1)LLCT manifold directly and/or indirectly and contribute to the emission in the visible range.