Transition Metal Ion Complexes Research Articles

Yellow-to-brown and yellow-to-green electrochromic devices based on complexes of transition metal ions with a triphenylamine-based ligand.

Transmissive-to-colored electrochromism has been achieved by combination of MLCT of transition metal complexes with the electrochromic properties of ligand molecules. The color transitions were from yellow to dark brown for the Fe(ii) complex, yellow to orange to bluish-green for the Co(ii) complex and yellow to green for the Zn(ii) complex. By using a metal ion-ligand coordination approach, the self-assembly of hydrazone-based ligands containing a triphenylamine group with appropriate metal salts (FeCl2, Co(ClO4)2 and Zn(BF4)2) produced novel complexes of the general formula [ML2]X2. The isolated complexes were characterized by spectroscopic methods, and the Co(ii) complex also by X-ray diffraction analysis. Thin films of the complexes have been obtained by a spray-coating method and they were used in the construction of electrochromic devices, which showed good electrochromic stability, a high color contrast of 47.5% for Fe(ii), 37.2% for Co(ii) and 33.7% for Zn(ii) complexes and fast coloring and bleaching times.

Synthesis and spectral study of mixed ligand complexes of Chromium(III) dibasic tridentate schiff schiff bases as primary and naphthoic acid as co-ligand

The transition metal complexes of Schiff bases have been widely researched on account of their importance as biochemical,analytical and antimicrobial reagent. Herein, the transition metal ion complexes of Cr(III) with dibasic tridentae Schiff bases derived by condensation of thiosemicarbazide with acetoacetanilide as primary ligand and 1-hydroxy-2-naphthoic acid as co-ligand have been prepared. The mixed ligand complexes of the above mentioned metal ion were characterized by analytical, magnetic and electronic spectral study. The transition metal complexes were also evaluated for antifungal activity against Drechslera tetramera, Fusarium-oxysporum and Macrophomia phoseoli at different concentrations.

The electronic structure of the aqueous permanganate ion: aqueous-phase energetics and molecular bonding studied using liquid jet photoelectron spectroscopy

Permanganate aqueous solutions, MnO4-(aq.), were studied using liquid-micro-jet-based soft X-ray non-resonant and resonant photoelectron spectroscopy to determine valence and core-level binding energies. To identify possible differences in the energetics between the aqueous bulk and the solution-gas interface, non-resonant spectra were recorded at two different probing depths. Similar experiments were performed with different counter ions, Na+ and K+, with the two solutions yielding indistinguishable anion electron binding energies. Our resonant photoelectron spectroscopy measurements, performed near the Mn LII,III- and O K-edges, selectively probed valence charge distributions between the Mn metal center, O ligands, and first solvation shell in the aqueous bulk. Associated resonantly-enhanced solute ionisation signals revealed hybridisation of the solute constituents' atomic orbitals, including the inner valence Mn 3p and O 2s. We identified intermolecular coulombic decay relaxation processes following resonant X-ray excitation of the solute that highlight valence MnO4-(aq.)-H2O(l) electronic couplings. Furthermore, our results allowed us to infer oxidative reorganisation energies of MnO4˙(aq.) and adiabatic valence ionisation energies of MnO4-(aq.), revealing the Gibbs free energy of oxidation and permitting estimation of the vertical electron affinity of MnO4˙(aq.). Finally, the Gibbs free energy of hydration of isolated MnO4- was determined. Our results and analysis allowed a near-complete binding-energy-scaled MnO4-(aq.) molecular orbital and a valence energy level diagram to be produced for the MnO4-(aq.)/MnO4˙(aq.) system. Cumulatively, our mapping of the aqueous-phase electronic structure of MnO4- is expected to contribute to a deeper understanding of the exceptional redox properties of this widely applied aqueous transition-metal complex ion.

Small Molecules in Light‐Emitting Electrochemical Cells: Promising Light‐Emitting Materials

AbstractLight‐emitting electrochemical cells (LECs) are solid‐state lighting devices that convert electric current to light within electroluminescent organic semiconductors, and these devices have recently attracted significant attention. Introduced in 1995, LECs are considered a great breakthrough in the field of light‐emitting devices for their applications in scalable and adaptable fabrication processes aimed at producing cost‐efficient devices. Since then, LECs have evolved through the discovery of new suitable emitters, understanding the working mechanism of devices, and the development of various fabrication methods. LECs are best known for their simple architecture and easy, low‐cost fabrication techniques. The key feature of their fabrication is the use of air stable electrodes and a single active layer consisting of mobile ions that enable efficient charge injection and transport processes within LEC devices. More importantly, LEC devices can be operated at low voltages with high efficiencies, contributing to their widespread interest. This review provides a general overview of the development of LECs and discusses how small molecules can be utilized in LEC applications by overcoming the use of traditional lighting materials like polymers and ionic transition metal complexes. The achievements of each study concerning small molecule LECs are discussed.

Dielectric properties of natural rubber/polyethylene oxide block copolymer complexed with transition metal ions

Transition metal ion complexes of natural rubber/polyethylene oxide block copolymer (NR/PEO block copolymer, BC) are prepared by the process of adsorption in aqueous solutions and subjected to electrical analysis and XRD studies. AC conductance, impedance, dielectric relaxation and modulus have been measured as a function of frequency. The conductivity shows a linear relation with frequency. Among the complexes studied, BC–Co(II) shows the highest conductivity, while BC–Cu(II) shows the lowest value which may be due to different coordination pattern adopted. The Nyquist plot of impedance shows that except BC and BC–Cu(II), other samples give single skewed semicircles, while the former two yield arc bending towards the abscissa. The relaxation studies indicate electrode polarisation effect at lower frequencies and ion migration at higher frequencies. Argand plot indicates the presence of viscoelastic relaxation, and a distribution of relaxation time occurs in all the samples. XRD results support the electrical properties observed for the BC and the complexes.

Recent Progress in White Light‐Emitting Electrochemical Cells

AbstractSolid‐state white light‐emitting electrochemical cells (LECs) exhibit the following advantages: simple device structures, low operation voltage, and compatibility with inert metal electrodes. LECs have been studied extensively since the first demonstration of white LECs in 1997, due to their potential application in solid‐state lighting. This review provides an overview of recent developments in white LECs, specifically three major aspects thereof, namely, host–guest white LECs, nondoped white LECs, and device engineering of white LECs. Host–guest strategy is widely used in white LECs. Host materials are classified into ionic transition metal complexes, conjugated polymers, and small molecules. Nondoped white LECs are based on intra‐ or intermolecular interactions of emissive and multichromophore materials. New device engineering techniques, such as modifying carrier balance, color downconversion, optical filtering based on microcavity effect and localized surface plasmon resonance, light extraction enhancement, adjusting correlated color temperature of the output electroluminescence spectrum, tandem and/or hybrid devices combining LECs with organic light‐emitting diodes, and quantum‐dot light‐emitting diodes improve the device performance of white LECs by ways other than material‐oriented approaches. Considering the results of the reviewed studies, white LECs have a bright outlook.

Mixed Ligand Complexes of Transition Metal Ions with Selective Bio-Ligands in Surfactant-Water Mixtures

Chemical speciation of ternary complexes of L-arginine and L-aspartic acid with essential transition metal ions was studied pH metrically. The following MLX, MLXH and ML2X ternary species are detected and reported in this paper. The existence of different ternary species is established from modeling studies using the computer program MINIQUAD75. The relative concentrations (M: L: X=1:2:2, 1:2:4, 1:4:2) and stabilities of the ternary species are compared with those of binary species. The extra stability associated with the ternary complexes is attributed to factors such as charge neutralization, chelate effect, stacking interactions and hydrogen bonding. Trend in variation of stability constants with the change in the mole fraction of the surfactant in various micellar media is explained on the basis of electrostatic and non-electrostatic forces. Distribution diagrams in relation to pH and plausible structures were presented.

One Pot Microwave Induced Synthesis, Characterization and Antibacterial Activity of Tetrazamacrocyclic Complexes of Transition Metal Ions of Bio-Inorganic Relevance

Two new series of metal complexes, [M(C18H16N4O4)·2H2O] (CH3COO−)2 and [M(C22H24N4)·2H2O](CH3COO−)2, where M= Co2+/Ni2+/ Cu2+ have been prepared under microwave irradiation condition using microwave synthesizer. All the synthesized compounds were characterized by melting point determination of recrystallized samples, running single spot on TLC, elemental analyses, IR, UV-visible spectral studies. Synthesized macrocyclic complexes have been tested for their antibacterial activity against two bacteria Klebsiella pneumoniae and Escherichia coli by adopting disk diffusion method. The antibacterial activity was compared with amikacin antibiotic and it has been found that the complexes exhibited potential antibacterial activity. From the antibacterial studies, it has been found that the copper complexes were more effective on the microorganism in comparison to Ni(II) and Co(II) complexes.

Modeling Solid State Stability for Speciation: A Ten-Year Long Study.

Speciation studies are based on fundamental models that relate the properties of biomimetic coordination compounds to the stability of the complexes. In addition to the classic approach based on solution studies, solid state properties have been recently proposed as supporting tools to understand the bioavailability of the involved metal. A ten-year long systematic study of several different complexes of imidazole substituted ligands with transition metal ions led our group to the definition of a model based on experimental evidences. This model revealed to be a useful tool to predict the stability of such coordination complexes and is based on the induced behavior under thermal stress. Several different solid state complexes were characterized by Thermally Induced Evolved Gas Analysis by Mass Spectrometry (TI-EGA-MS). This hyphenated technique provides fundamental information to determine the solid state properties and to create a model that relates stability to coordination. In this research, the model resulting from our ten-year long systematic study of complexes of transition metal ions with imidazole substituted ligands is described. In view of a systematic addition of information, new complexes of Cu(II), Zn(II), or Cd(II) with 2-propyl-4,5-imidazoledicarboxylic acid were precipitated, characterized, and studied by means of Thermally Induced Evolved Gas Analysis performed by mass spectrometry (TI-EGA-MS). The hyphenated approach was applied to enrich the information related to thermally induced steps, to confirm the supposed decomposition mechanism, and to determine the thermal stability of the studied complexes. Results, again, allowed supporting the theory that only two main characteristic and common thermally induced decomposition behaviors join the imidazole substituted complexes studied by our group. These two behaviors could be considered as typical trends and the model allowed to predict coordination behavior and to provide speciation information.

Realization of Red Iridium-Based Ionic Transition Metal Complex Light-Emitting Electrochemical Cells (iTMC-LECs) by Interface-Induced Color Shift.

Red ionic iridium-based transition metal complex light-emitting electrochemical cells (iTMC-LECs) with emission centered at ca. 650 nm, maximum efficiency of 0.3%, maximum brightness above 650 cd m-2, and device lifetime well above 200 and 33 h at brightness levels of 10 and 210 cd m-2, respectively, are realized by the introduction of a p-type polymer interface to the standard design of [Ir(ppy)2(pbpy)]+[PF6]- (Hppy = 2-phenylpyridine, pbpy = 6-phenyl-2,2'-bipyridine) iTMC-LEC. The unexpected color shift from yellow to red is studied in detail with respect to operation conditions and material combination. The experimental data suggest that either exciplex formation or subordinate, usually suppressed optical transitions of the iTMC might become activated by the introduced interface, causing the pronounced red shift of the peak emission wavelength.

Cationic IrIII Emitters with Near-Infrared Emission Beyond 800 nm and Their Use in Light-Emitting Electrochemical Cells.

Solid-state near-infrared (NIR) light-emitting devices have recently received considerable attention as NIR light sources that can penetrate deep into human tissue and are suitable for bioimaging and labeling. In addition, solid-state NIR light-emitting electrochemical cells (LECs) have shown several promising advantages over NIR organic light-emitting devices (OLEDs). However, among the reported NIR LECs based on ionic transition-metal complexes (iTMCs), there is currently no iridium-based LEC that displays NIR electroluminescence (EL) peaks near to or above 800 nm. In this report we demonstrate a simple method for adjusting the energy gap between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) of iridium-based iTMCs to generate NIR emission. We describe a series of novel ionic iridium complexes with very small energy gaps, namely NIR1-NIR6, in which 2,3-diphenylbenzo[g]quinoxaline moieties mainly take charge of the HOMO energy levels and 2,2'-biquinoline, 2-(quinolin-2-yl)quinazoline, and 2,2'-bibenzo[d]thiazole moieties mainly control the LUMO energy levels. All the complexes exhibited NIR phosphorescence, with emission maxima up to 850 nm, and have been applied as components in LECs, showing a maximum external quantum efficiency (EQE) of 0.05 % in the EL devices. By using a host-guest emissive system, with the iridium complex RED as the host and the complex NIR3 or NIR6 as guest, the highest EQE of the LECs can be further enhanced to above 0.1 %.

Anti-Cancer Screening of Some Transition Metal Ion Complexes with Coumarin Derivatives

In this study, an equal amount of -4-methyl-5,7-(bis p-chlorophenyl azo) coumarin (ligand 6-hydroxy) and copper, cobalt, and nickel (metals) were reacted to synthesize the respective metal ion complexes. The synthesized metal complexes were characterized using various approaches such as CHN elemental analysis, 1H-NMR, mass spectral data, and FTIR. The outcome of the spectroscopic analysis showed the coordination of the ligand to the metal ion that is in the complexes through hydroxyl group; the data also showed the complexes to exhibit octahedral geometry. Further studies on the solid complexes were performed by molar conductance where all the synthesized metal complexes exhibited nonconductive properties in chloroform. An MTT-based cytotoxicity screening of the complexes against lung and breast cancer cells showed Co(II), Cu(II), and Ni(II) complexes to exhibit cytotoxic activity against the studied cells at low concentrations.

Coordination Modes, Oxidation, and Protonation Levels of 2,6-Pyridinediimine and 2,2':6',2'́-Terpyridine Ligands in New Complexes of Cobalt, Zirconium, and Ruthenium. An Experimental and Density Functional Theory Computational Study.

The syntheses and molecular and electronic structures of the following complexes have been established by single crystal X-ray crystallography and UV-vis-NIR spectroscopy, and verified by density functional theory calculations (DFT B3LYP): [(η5-Cp)2ZrIV(tpy2-)]0 ( S = 0) 1, [(η5-Cp)2ZrIV(OMepdi2-)]0 ( S = 0) 2, [CoII(OMepdi•)(η2-BH4)]0 ( S = 0) 4, [RuII(OMepdi-H)Cl(PPh3)2]0 ( S = 0) 5, cis-[RuII(OMepdi0)Cl2(PPh3)]0 ( S = 0) 6, and [RuII(η2-OMepdi0)(η2-OMepdi-H)2]0 ( S = 0) 7, with (tpy0) being neutral 2,2':6',2'́-terpyridine, (tpy•)1- its π radical anion, (tpy2-)2- its dianion; (OMepdi0) neutral 2,6-bis(4-methoxyphenylmethylimine)pyridine, (OMepdi•)1- its radical anion and (OMepdi2-)2- its dianion; (OMepdi-H)1- represents the deprotonated form of the (OMepdi0) ligand where deprotonation takes place at the meta-position of the pyridine ring. Density functional theory calculations using the B3LYP functional were performed, establishing geometry optimized molecular and electronic structures. The structural parameter Δ = [(average distance Cpy-Cimine) - (av. distance Cpy-Npy + av. distance Cimine-Nimime)] is introduced for the characterization of the oxidation level of pdi (and analogously of tpy) ligands of M(pdi) (or M(tpy)) motifs for first row transition metals. The M(L0) unit in second and third row low-valent transition metal ion complexes may exhibit significant π-backdonation M → L0 structural effects.

Design and Realization of White Quantum Dot Light-Emitting Electrochemical Cell Hybrid Devices.

The simple device architecture as well as the solution-based processing makes light-emitting electrochemical cells (LECs) a promising device concept for large-area flexible lighting solutions. The lack of deep-blue emitters, which are, at the same time, efficient, bright, and long-term stable, complementary to the wide variety of yellow-orange-emitting LECs, hampers the creation of white LECs. We present a hybrid device concept for the realization of white light emission by combining blue colloidal quantum dots (QDs) and an Ir-based ionic transition-metal complex (iTMC) LEC in a new type of white QD-LEC hybrid device (QLEC). By careful arrangement of the active layers, we yield light emission from both the blue QDs and the yellow iTMC emitter already at voltages below 3 V. The QLEC devices show homogeneous white light emission with high color rendering index (up to 80), luminance levels above 850 cd m-2, and a maximum external quantum efficiency greater than 0.2%.

Synthesis, characterization, DFT and antimicrobial studies of transition metal ion complexes of a new schiff base ligand, 5-methylpyrazole-3yl-N-(2́-hydroxyphenylamine)methyleneimine, (MPzOAP)

A new pyrazole based ‘NNO’ tridentate ligand, 5-methylpyrazole-3yl-N-(2́-hydroxyphenylamine)methyleneimine, (MPzOAP) was synthesized and characterized by elemental analyses, mass, IR, 1H NMR spectral parameters. The versatile coordination mode of the ligand was established by the synthesis of Co(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) metal ion complexes. These complexes were characterized by elemental analyses, conductance and magnetic susceptibility measurements, UV–Vis, IR, 1H NMR spectroscopy, PXRD and thermal analysis. The structures of the ligand and complexes were also investigated using the DFT method. The ligand structure contains the coordination function of the tertiary nitrogen atom of pyrazole ring, the azomethine nitrogen and the phenolic oxygen atom, suitably spaced for chelation with a metal ion and acting as a ‘NNO’ tridentate donor ligand. In vitro antimicrobial activity of the reported ligand and the metal ion complexes were screened and the mode of action was also studied by scanning electron microscopy (SEM) against some pathogenic bacteria.

A Series of Octahedral First-Row Transition-Metal Ion Complexes Templated by Wells-Dawson Polyoxometalates: Synthesis, Crystal Structure, Spectroscopic, and Thermal Characterizations, and Electrochemical Properties.

Three Wells-Dawson polyoxotungstates-based hybrid compounds of general formula [M(C3H7NO)6][{M(C3H7NO)5}2(μ-P2W18O62)]· nC3H7NO· n'H2O [with M = MnII (1), FeII (2), CoII (3) ; n = 2, 2, 3 and n' = 0, 0, 1, respectively] were synthesized at room temperature by a facile method and characterized by IR and 1H and 31P NMR spectroscopy studies, thermogravimetric analysis-differential scanning calorimetry thermal analyses, UV-vis, X-ray diffraction (XRD) powder and single-crystal XRD analyses, and cyclic voltammetry studies. From the X-ray study, it was established that the metal (M = Mn, Fe, Co) is located on an inversion center, being octahedrally coordinated to six dimethylformamide (DMF) molecules to form the complex cation [M(dmf)6]2+. Also, in the dinuclear complex anion [{M(dmf)5}2(μ-P2W18O62)]2-, the M atoms are coordinated to five DMF molecules through the oxygen atoms, while the sixth coordination site is occupied by a terminal oxygen atom of the Wells-Dawson anion [P2W18O62]6- that plays the role of a bridging ligand. The crystal components are connected through numerous weak C-H···O hydrogen bonds to construct a three-dimensional network. The UV-vis shows the two characteristic absorption bands for the three compounds at 266-268 and 297 nm. These two strong bands are attributed to the charge-transfer absorption band of Ot-W and Ob/c-W, respectively. Cyclic voltammetry study of compounds (1), (2), and (3) reveals at least two reduction reversible peaks ascribed to a Wells-Dawson cluster.

Controlling Ion Distribution for High-Performance Organic Light-Emitting Diodes Based on Sublimable Cationic Iridium(III) Complexes.

Sublimable charged iridium(III) complexes are becoming an attractive family of new phosphors and making their way into vacuum-evaporated-deposited organic light-emitting diodes, while it remains challenging to achieve high device performance. Here, we demonstrate a substantial mitigation of exciton quenchingnot only byreducing the dopant concentration, but also by controlling the ion distribution in the emissive material layers. We, therefore, achieved green luminescence with high brightness, superior efficiencies, and low driving voltages. Following this strategy, we further developed another six sublimable charged iridium(III) complexes and attained blue-green, yellow, and red-emitting devices with record-high performance. This study represents an important advance in the construction of bright electroluminescence from ionic transition metal complexes and shows their great promise in various optoelectronic applications.

Ionic Organic Small Molecules as Hosts for Light-Emitting Electrochemical Cells.

Light-emitting electrochemical cells (LEECs) from ionic transition-metal complexes (iTMCs) offer the potential for high-efficiency electroluminescence in a simple, single-layer device. However, LEECs typically rely on the use of rare metal complexes. This has limited their cost effectiveness and put constraints on their applicability. With a view to leveraging the efficient emission of these complexes while mitigating costs, we describe here a host/guest LEEC strategy that relies on the use of carbazole (Cz)-based organic small-molecule hosts and iTMC guests. Three cationic host molecules were prepared via the coupling of 1-(4-bromophenyl)-2-phenylbenzimidazole (PBI-Br) with Cz. This has allowed a comparison between the hosts bearing methoxy (PBI-CzOMe) and tert-butyl (PBI-Cz tBu) substituents, as well as an unsubstituted analogue (PBI-CzH). Cyclic voltammetry and UV-visible absorption revealed that allthree host materials have wide band gaps characterized by reversible oxidation and irreversible reduction events. On the basis of electronic structure calculations, the host highest occupied molecular orbital (HOMO) resides primarily on the Cz moiety, whereas the lowest unoccupied molecular orbital (LUMO) is located primarily on the phenyl-benzimidazolium unit. Photoluminescence analysis of thin-film blends of PBI-CzH with iTMC guests confirmed that the emission was blue-shifted relative to pristine iTMC films, which is consistent with what was seen in dilute dichloromethane solution.LEEC devices were prepared based on thin films of the pristine hosts, pristine guests, and 90%/10% (w/w) host/guest blends. Among these host/guest blends, LEECs based on PBI-CzH displayed the best performance, particularly when an iridium complex was used as the guest. The system in question yielded a luminance maximum of 624 cd/m2 at an external quantum efficiency of 3.80%. This result stands in contrast to what is seen with typical organic light-emitting diode host studies, where tert-butyl substitution of the host generally leads to a better performance. To rationalize the present observations, the host materials were subject to single-crystal X-ray diffraction analysis. The resulting structures revealed clear head-to-tail interactions in the case of both PBI-CzH and PBI-CzOMe. No such interactions were evident in the case of PBI-Cz tBu. Furthermore, PBI-CzH showed a relatively smaller spacing between the successive HOMO and successive LUMO levels relative to PBI-CzOMe and PBI-Cz tBu, a finding consistent with more favorable charge transport and energy transfer. The results presented here can help inform the design and preparation of host materials suitable for use in single-layer iTMC LEECs.

Toward High-Performance Vacuum-Deposited OLEDs: Sublimable Cationic Iridium(III) Complexes with Yellow and Orange Electroluminescence.

Great advances in the development of efficient luminescent materials are the driving force behind organic light-emitting diodes (OLEDs). Sublimable ionic transition-metal complexes (iTMCs) have emerged as a large family of new emissive dopants applied for vacuum-deposited OLEDs, while the achievement of excellent performance remains arduous. A series of novel sublimable cationic iridium(III) complexes have been designed and synthesized, containing an imidazole-type ancillary ligand and tetraphenylborate-type negative counter-ions with large steric hindrance and well-dispersed charges. The photophysical properties, electrochemical behaviors, and thermal stability are fully investigated and discussed, then demonstrated by theoretical calculations. Yellow- and orange-emitting OLEDs thereof are fabricated by vacuum evaporation deposition, realizing a high external quantum efficiency of up to 11 %, maximum brightness over 27.3×103 cd m-2 and low turn-on voltages below 2.4 V, among the best results of analogous phosphorescent OLEDs based on iTMCs. This work indicates the promising applications of sublimable iTMCs in state-of-the-art vacuum-deposited optoelectronic devices.

Photophysics, photochemistry and thermally-induced redox reactions of a (Pterin)rhenium(I) complex

In this work, we present a whole and deep study on the thermal redox and the photophysical and photochemical reactions of a tricarbonyl Re(I) complex coordinating Pterin, fac-ReI(CO)3(pterin)(H2O) (pterin = 2-amino-4-oxo-3H-pteridine). In aqueous solutions, the fluorescence of the complex is attributed to the emitting 1IL state (τemi ∼ 7.6 ns). In MeCN, however, the luminescence was ascribed to an overlapping dual emission from 1IL and 3MLCT states (τemi1 = 8.0 ns and τemi2 = 1.0 μs). Oxygen quenching of the 3MLCT based luminescence occurred with kq = 1.6 × 109 M−1 s−1. In glasses at 77 K, nevertheless, the 3MLCT prevailed over 1IL states. Flash photolysis experiments in aqueous solutions showed the spectrum of 3IL while in MeCN the presence of 3MLCT was evident. Pulse radiolysis experiments under oxidizing and reducing environments were performed in aqueous solutions of the Re-Pterin complex. By performing multivariate curve resolution − alternating least-squares (MCR-ALS), two species were identified under reducing conditions: an intermediate related to the semireduced radical of pterin ligand and the dihydrogenated [Re(CO)3(7,8-PtrH2)(H2O)] product. TD-DFT calculations helped to ascertain the nature of these species. Flash photolysis experiments where the excited states were reduced with triethylamine were in good agreement with pulse radiolysis experiments under reductive conditions. The oxidized transient spectrum was also obtained by pulse radiolysis, which compares very well with those published for Re(II) species, leading us to propose oxidation in the metal core as the reaction product of the transient under oxidizing conditions.The combination of different spectroscopic techniques along with the theoretical calculation allowed elucidating the nature, dynamics and reactivity of the excited states prevail in a Re-Pterin complex. This is of the particular importance considering that equivalent studies have not been reported for any other rhenium complex of substituted pterins nor for complexes of other transition metal ions of pterin derivatives.