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The photophysical properties of the emitting metal-to-ligand charge transfer (MLCT) excited states of the complexes are characterized by using the time-dependent theory of Raman scattering. The mode-specific vibrational parameters are used to calculate the vibrational contributions to the radiative and nonradiative decay rate constants.

Research has been consucted on the applications of time-resolved infrared spectroscopy in excited-state electronic and molecular structures. The use of this spectroscopy in the nu(CO) region in combination with synthetic manipulation, density functional calculations and emission measurements in investigating metal-to-ligand charge-transfer excited state electronic structure in different complexes is described.

Time resolved infrared (TRIR) measurements offer the unique opportunity to directly probe the excited-state dynamics of [Re(LL)(CO)(sub 4)](super +). The data demonstrate formation of a unique excited state for [Re(LL)(CO)(sub 4)](super +) species followed by loss of a single cabonyl ligand to form a fac-Re(CO)(sub 3) solvento complex.

A relative intermediate I(sub c.) relevant to the CO migratory insertion step of alkene hydroformylation catalyzed by phosphine-modified cobalt carbonyl is generated by Photodecarbonylation of the acetyl complex (eta(super 1)-CH(sub 3)CO)Co(CO)(sub 3)(PPh(sub 3) (A(sub c.). Time-resolved IR spectroscopy indicates I to be the eta(super 2)-acetyl complex (eta(super 2)-CH(sub 3)-CO(Co)(CO)(sub 2)(PPh(sub 3)), which reacts competitively by methyl migration to give CH(sub 3)-Co(CO)(sub 3)(PPh(sub 3)) (MCo) and trapping by CO to re-form A(sub c.).

The first quaternary selenophosphate phases of thorium are prepared using the flux method and characterized by X-ray defraction and vibrational spectroscopy. It is expected that varying flux composition would produce new phases with other chalcophosphate or polychalcogenide anions.

The existence of a redox-separate state during the excited-state electron transfer in chromophore-quencher complex fac-(Re(Aqphen)(CO)3(py-PTZ))(super +) has been examined through several spectroscopic methods. Aqphen is a dppz derivative with a pendant quinone acceptor at the terminus of a rigid ligand framework. Time-resolved infrared measurements on the chromophore-quencher complex reveal that the excited electron is localized on the quinone part of the ligand while the acceptor is in a redox-separated state.

The Krohnke synthetic methodology was used to prepare 4'-(ferrocenyl)-2,2':6',2'-terpyridine (Fctpy) and 4'-(4-pyridyl)-2,2':6',2'-terpyridine (pytpy) from the corresponding ferrocene- and pyridinecarboxaldehyde and 2-acetylpyridine. Metal complexes were also prepared and characterized. The influence of the ferrocenyl site on excited-state decay was discussed and an excited-state energy level diagram proposed.

Time-resolved vibrational spectroscopies were used on a series of questions connected with excited-state structure in the metal-to-ligand charge transfer (MLCT) excited states of polypyridyl complexes. These complexes contain bpy ligands which are either symmetrically or unsymmetrically derivatized with electron-withdrawing ester or amide substituents. Vibrational data obtained elucidated on the identification of the acceptor ligand, the localization or delocalization of the excited electrons, polarization in unsymmetrically subsituted acceptor ligands and excited-state electronic distribution.

The time-resolved infrared spectrum of [Ru(phen)3]2+* in the fingerprint region was examined. The spectra included information about both chromophoric and ancillary ligands since the experiment is independent of the requirement of resonance enhancement. Data gathered provided evidence for the localized description of [RuIII(phen)3]3+* on the 100 ns time scale. Results also aided in the interpretation of the time-resolved resonance Raman spectrum of the ligand and gave insight into electronic distribution in the excited state.

The characterization of excited states after electronic excited inorganic complexes in solution was analyzed using time-resolved resonance Raman and time-resolved infrared spectroscopies. The effect of changes in equilibrium displacement was represented by a potential energy diagram. Results showed that transient vibration spectroscopies can effectively elucidate the electronic and molecular structures associated with excited states and photochemical intermediates.

The bridging ligand 2,2':3',2'':6'',2'''-quaterpyridine was observed to have two inequivalent metal binding sites (A and B) which perturb the metal-to-ligand charge transfer (MLCT) energy levels of the attached Re(I) or Ru(II). Time-resolved infrared difference spectra of ((bpy)2Ru(II)ABRe(I)(CO)3Cl)2+ were in agreement with a lowest lying Ru(III)-AB*- MLCT state, while spectra of ((CO)3ClRe(I)ABRu(II)(bpy)2)2+ indicated the presence of both Re(II)-AB*- and Ru(III)-AB*- MLCT excited states.

Metal-to-ligand charge transfer through time-resolved infrared (TRIR) was demonstrated in a study conducted on [Ru(bpy)(sub3)](super2+) and [Re(bpy)(CO)(sub3)(4-Etpy)](super+) (bpy is 2,2'-bipyridine) and (4-Etpy is 4-ethylpyridine). TRIR was then used in the fingerprint region from 1400 to 1625 cm(super-1) for transition metal complex at their excited states. Findings provided significant insight for electronic and molecular structure in the excited state, which focused on the directions and magnitudes of the infrared shifts.

The group-state of cluster complexes of [M6X8Y6]2- with binary and ternary metal-halide compounds was analyzed by resonance Raman spectroscopy. The polarized (TBA)2[Mo6Cl8Cl6] complex exhibits two symmetric Raman bands (A1g) with an Mo6 breathing mode. The Mo and W cluster complexes also exhibited similar metal-halide force constants and the ratio of symmetric metal-halide Raman shifts are equal to the square root of the inverse mass ratios of halogens.

The blue dimer [(bpy)2(H2O)RUIIIORuIV(OH)(bpy)2](ClO4)4 is composed of two Ru atoms that are connected by one oxygen atom. Two bypiridine ligands, an oxo atom and an oxygen atom are octahedrally coordinated with the two Ru atoms. The bypiridine ligands exhibit a cis geometry with each Ru atom and the coordinating atoms are located away from the bridging oxygen atoms. The mu-oxo bridge produces a strong electronic coupling between the two Ru atoms which bends the Ru-O-Ru bond angle to 120 degrees.

Symmetrical trans-(Ru(tpy)(py)2(PPh3))2+ complexes can be synthesized from bis(trifluoroacetate) precursor 1. Electrochemical and ultraviolet visible spectroscopic analysis of photophysical and photochemical properties of these polypyridine complexes show that these complexes have a short excited state lifetime ranging from 1.1-11.0 micro seconds at 90-270 kelvin and the dd states are responsible for this property.

Photoinduced electron transfer in a ligand-bridged Re(sup I)-Re(sup I) complex was investigated. Specifically, the linked donor-acceptor complex MQ(sup +) (CO)3Re(sup I)(bbpe)Re(sup I)(CO)3(py-PTZ) (sup 3+) was subjected to metal-to-ligand charge transfer excitation by laser flashing. The process resulted in cross-bridge redox splitting, a state that was verified by transient resonance Raman measurements.

Transient UV-visible and resonance Raman spectroscopic studies of the metal-to-ligand-charge transfer (MLCT) excited states of two ligand-bridged complexes indicate that excited electron in the Ru complex exhibits a delocalization over the electron acceptor ligand 1, (( 2-bis-4-(4'-methyl)-2,2'-bipyridyl)ethene). This delocalization increases the life times of the excited states, and decreases the vibrational overlap between states and the rate constant for nonradiative decay.

A procedure based on the interaction of surface hydroxyls with carboxylic acid groups helps analyze electron transfer and excited state properties of polypyridyl complexes of Ru(II) attached to metal oxide surfaces or glass surfaces of molecules. Cyclic voltammetric studies help examine surface attachment and stability of the surface-attached couples. Atomic-force microscopic studies reveal the roughened nature of metal oxide surfaces. Electrochemical measurements help determine thermodynamic parameters for surface binding. Photochemical studies indicate the occurrence of lateral electron and energy transfer across the surface.

Photophysical behavior of the redox-active synthetic amino acids dyads and trifunctionalized amino acids are examined in CH(3)CN after nanosecond laser excitation. These complexes employ anthraquinone as the electron acceptor. Irradiation induces a series of electron-transfer reactions leading to redox separation.

Time-resolved resonance Raman (TR3), and transient UV/vis absorption spectroscopy, which facilitated the study of metal to ligand charge-transfer excited states of the polychromophoric complexes, revealed the presence of Ru(I) and Ru(III) centers on the polynuclear complex excited states. These complexes are used in the design of a molecular device that facilitates visible sensitization of semiconductors, and oligomers which behave as molecular conduits for long-range energy transfer.

Metal to ligand charge-transfer excitation occurs in the chromophore-quencher complexes cis-((bpy)2Os(II)(CO)(MQ+))3+, as indicated by transient resonance Raman spectra. The monoquant ligand is indicated by the transient spectra of the complex. A coplanar geometry is exhibited by the ligand and two pyridyl rings which are delocalized to the excited state.

A series of redox-active lysines and related model compounds based on polypyridyl ruthenium complexes are prepared and characterized photophysically. Transient absorption spectroscopy is used in the observation of the redox-separated state, enabling the analysis of the kinetic behavior of these systems and the factors that influence the lifetime of the redox separated state.

The photophysical and spectroscopic properties of polynuclear complexes with cyano-bridged ruthenium polypyridine units are studied to investigate the extent of electronic interaction between the metal centers of these systems. A comparison of the infrared spectra of the mixed-valence forms of these polynuclear complexes with those of the mixed-valence ions of the type (M-NC-M'(bpy)2-CN-M)(super 6+/4+) and (NC-M'(bpy)2-CN-M)(super 3+/2+), where M = (Ru(NH3)5)(super 2+/3+) and M' = RuII, OsII and ReI, is also undertaken.

Time-resolved resonance Raman spectroscopy of (Ru(phen)3)2+ (phen = 1,10-phenanthroline) in CH3CN at 298 deg K revealed that ground-state bands dominate even at high laser irradiances. However, when compared with the resonance Raman spectrum of (Ru(II)(phen*-)(phen)2)+ generated electrochemically, bands for phen*- can be found in the excited-state spectrum at 1130, 1272 and 1585/cm. The excited-state spectrum is in agreement with the localized description, (Ru(III)(phen)2(phen*-))2+.

Free N-methyl-4,4'-bipyridium radical (MQ.) exhibit visible absorption at 360 and 600 nanometer due to pi to pi* and pi* to pi* (MQ.) transitions. Raman measurements of MQ., ((bpy)2Ru(MQ.)2)(super 2+) and ((bpy)2Os(CO)(MO.))(super 2+) reveal the presence of novel Ru(II) and Os(II) bands at 468 and 426 nanometer arising due to M(II)-(d-pi) to MQ.(pi*) metal-to-ligand charge transfer transition. Suitable intensity changes occur at 251 per centimeter for Raman bands.

A general synthetic procedure for the production of heteroleptic tris-bidentate polypyridyl (pp) complexes, (Ru pp pp' pp'')2+ has been developed. The precursor (Ru CO 2 Cl 2)n and a bidentate pp ligand were heated at reflux in EtOH or MeOH, then converted to Ru(pp)(CO)2(CF3SO3)2 by heating in trifluoromethanesulfonic acid. The (Ru pp pp' pp'')2+ cations were formed by heating the (Ru pp pp' CO 2)2+ cations which were precipitated from the triflato species with trimethylamine N-oxide in 1,2-dimethoxyethane in the presence of a third pp ligand.

The synthesis and reactivity of a phosphonated adsorbed ruthenium, Ru(VI)-oxo complex are described. The stepwise oxidation of the complex is very useful for the oxidation of benzyl alcohol to benzaldehye.

The preparation of four arrays of helical oligoproline arrays, consisting of 16,17, 18 and 19 amino acid residues is described. The arrays, which systematically in the distance between the redox-active metal complex and phenothiazine sites find use in photophysical studies to provide insight into the distance dependence of electron transfer.

The time scale for triplet-triplet energy transfer between a Ru(II) chromophore and a ligand bound anthracene acceptor in [Ru(super II)(dmb)(sub 2)(bpy-an)](super 2+) is measured using femtosecond transient absorption spectroscopy. The time-resolved experiments show the presence of fast, sub-100ps energy transfer to the anthracene occurring on two characteristic time scales of 23 and 72 ps.

The characteristic patterns of infrared bands in v(CO) region are examined in the time-resolved infrared (TRIR) spectra of fac-rhenium tricarbonyl complexes. The patterns are interpreted by the combination of experimental time-resolved infrared (TRIR) data with density functional theory (DFT) calculations.

The density functional theory (DFT) calculations are the basis for the assignments and band shifts in the metal-to-ligand charge transfer (MLCT) excited state of the series of complexes. The variation in energy gap influences the excite-state geometries and electronic structures.

The nanosecond and the picosecond time-resolved optical spectroscopy is explained. When rhodium( I) complexes are subjected to photoexcitation, nanosecond time-resolved infrared spectroscopy is generated.

The extension of the [micro]-oxo-based water oxidation chemistry to metal oxide surfaces is described based on the phosphonate-modified complex. The results have shown that single electron transfer activation of multiple electron transfer and water oxidation can be transferred to the electrode interface on oxide electrodes.

Research has been conducted on the oligomeric metal complexes. The single stereospecific photosubstitution of the CO ligand trans to a bridging ligand has been investigated in a symmetric dimeric precursor in preparing the route to liner oligomeric Re(I) polypyridine complexes and the results are discussed.

Some of the results of a study conducted by W. Chen, et al, on the interaction between (Ru(phen)2dppz)2+ and DNA invite comment. The lowest excited state of ruthenium(II) dppz complexes generated confusion resulting from data for rhenium-(I) dppz complexes. Chen's suggestion on the identity of the species responsible for TR2 spectra was also unlikely. In addition, the researchers should have considered the detection of the pseudo-steady-state population during a 10 ns laser pulse.

The excited-state spectra in three polypyridyl complexes of rhenium(I) were determined. Time-resolved infrared difference spectra have been obtained by step-scan Fourier transform infrared spectroscopy. The results showed that the lowest-lying excited state for the complexes were a metal-to-ligand charge transfer (MLCT), a 3(pi)(pi)* states and a mixture of ligand-based and MLCT states.