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The synthesis of two crown ether chemosensors featuring a boron azadipyrrin chromophore is reported. The analysis has shown that boron azadipyrrins, functionalized with an 18-crown-6 ring, makes an excellent visible chemosensors for the marine toxin saxitoxin, the most toxic component of paralytic shellfish poisons.

A series of ferrocenyl derivatives with TCF-type acceptors are designed, and their electronic structures and one- and two-photon absorption properties are investigated. Results reveal that ferrocenyl derivatives with TCF-type acceptors are promising candidates for two-photon absorptions (TPA) materials.

A simple multiplex vibrational spectroscopic imaging technique was described based on employing chirped femtosecond pulses in a coherent anti-Stokes Raman scattering (CARS) scheme. Simulated chirped (c-) CARS spectra match the experimental results, quantifying the dependence of high spectral resolution on the properties of chirped pulse.

Pyrene chromophores functionalized to gold nanoparticles using methylene groups of varying chain length were prepared. A detailed investigation was conducted on the nanoparticle-chromophore and interchromophore interactions. The emission spectra studies indicated that the local environment close to the surface of Au nanoparticle was more polar compared to the bulk medium.

Asymmetric energy transfer by direct observation of (super 1)B emission in the heterodimer mutant and by the observation of the rise of (super 1)D emission following preferential excitation of (theta)(sub M) or B(sub L) in the M202HL/M182HL mutant is presented. The results suggest that singlet energy transfer from the monomeric chromophores along the L and M branches to the heterodimer special pair is asymmetric and faster.

An examination is done on the optical absorption spectra, which were calculated in liquid solutions at ambient temperature for comparatively nonpolar chromophores -- polymethine dyes, polycyclic hydrocarbons and tetrapyrrolic compounds. In conclusion, the long-range electrostatic interactions must lead to the slope values less than Bt.

The circular dichroism (CD) and transient absorption spectroscopy are used to study the functional role of the covalent attachment of the bilin chromophores biliverdin (BV) and phycocyanobilin (PCB) for phytochrome Agp1 from Agrobacterium tumefaciens. The results revealed that the [P.sub.r] to [P.sub.fr] photoconversion in the BV and PCB adducts of Agp1 involved the same relaxation processes and hence are governed by specific protein-cofactor interactions rather than by the chemical structure of the chromophore or the mode of attachment.

Single-molecule (SM) spectroscopy is used for studying exciton-like intramoelcular charge transfer (ICT) coupling dynamics in two model dendritic systems containing branched ICT interactions. The fluorescence from the delocalized ICT excited state over two branches in push-pull molecules is observed at the SM level.

The spectral dynamics of single photosystem I (PSI) complexes is strongly reduced in its rate by the exchange of the solvent from [H.sub.2]O to [D.sub.2]O. The observed changes in the spectral diffusion are attributed to exchangeable protons at the amino acids and structural water molecules in the chromophore binding pocket.

Single molecule spectroscopy of single oligomers and polymer chains are compared. The actual shape of the individual chromophore in phenylene-vinylenes dominates the spectroscopic properties.

DNA microarrays are used for creating new Ag nanoclusters fluorophores with excellent spectral and photophysical properties. The biodiversity inherent in single stranded DNA via modification of base sequence and strand length has enabled the optimization and identification of new Ag nanocluster-based emitters for single molecule spectroscopy and imaging.

The temperature dependence of the conformational change of single proteins between 5 and 18 K is described. The fluorescence excitation spectrum of single chromophores has shown the conformational change to be either a thermally activated motion over a potential barrier of around 100 J/mol or a tunneling of a proton through a thermally inaccessible high barrier.

The excited state behavior of synthetic DNA dumbbells possessing stilbenecarboxamide linkers is investigated. This is the first example of symmetry breaking in an A-B-A system via bridge mediated hole-hopping mechanism.

Femtosecond transient absorption and fluorescence upconversion experiments are used for examining the photoinduced dynamics of the meta isomer of the green fluorescent protein chromophore and its O-methylated derivative. The meta compounds have undergone ultrafast intermolecular excited-state proton transfer, which has competed with isomerization, in aqueous solutions.

The bioinspired dyad molecule is studied by using time-resolved spectroscopies and its structure, spectrum and dynamics is compared to the LH2 complex from Rhodopseudomonas acidophila. The caroteno-purpurin dyad is found to be an ideal case for the coherent-control study, as it has a clear branching of the energy flow between two competing pathways leading to two different processes, energy transfer (ET) and loss channel (IC).

Nuclear magnetic resonance (NMR) parameters of rhodopsin chromophore are examined in the dark state of the protein and in the early photointermediate bathorhodopsin by using first-principles molecular dynamics simulations and NMR chemical shift calculations. The studies have shown that both the [super 13]C and the [super 1]H NMR chemical shifts are insensitive to the protonation state of Glu181, an ionizable amino acid side chain located in the vicinity of the isomerizing 11-cis bond.

Density functional theory is used for examining the photoinduced electron transfer (ET) and the absorption spectrum for a bis-naphthalimide spermine conjugate. The electronic coupling matrix elements are estimated and the analysis has shown that the strongest absorption is due to the local excitation of the naphthalimide chromophore.

The behavior, structures and electronic excitations of various red fluorescent proteins (RFPs) and green fluorescent proteins (GFPs) are discussed. The analysis reveals that a protein environment is very important while determining the conformation of chromophores in these proteins.

The two-photon absorption bands for the lowest excitations in various fluorescent proteins are measured. These proteins are found to exhibit multiphoton excitation and hence can be used in bioimaging.

The phenomenon and the resonance enhancement of two-photon absorption (2PA) in fluorescent proteins are discussed.

The synthesis and characterization of 1,4- and 1,3-benzene-bridged N,N'-diisopropyl-6-oxoverdazyls is described. The reaction provides insight into the intramolecular electronic and magnetic coupling between verdazyl chromophores.

Multiparameter fluorescence spectroscopy and model-free statistical analysis methods are used for analyzing the complex quantum dot (QD)-dye hybrid Forster resonance energy transfer (FRET) systems at the single-particle level and also excited-state dynamics in multichromophore systems. The analysis has suggested an approach for using QD-dye hybrid FRET-based sensors in single particle applications.

The photophysics of platinum acetylide chromophores with strong two-photon absorption cross-sections is explored by examining the synthesis and spectroscopic characterization of a series of platinum acetylide complexes. It is shown that the photophysical processes are the same for either one- or two-photon excitation.

A breakdown of the standard nonradiative decay pathways were found to give rise to several single, dominant and lowest energy emissive excited state in ruthenium complexes. The complexes exhibited dual emission characteristics, as the emissive characteristics act as a function of covalent and noncovalent modification.

The synthesis of a new type of 6-propionyl-2-dimethylaminonaphthalene (PRODAN)-labeled nucleoside ([super PDN]X), (X = U, C, A and G) and the photochemical properties of oligodeoxyribonucleotides (ODNs) containing them are reported. The results have shown that the unique photochemical character of [super PDN]X is applicable to the efficient typing of single-nucleotide polymorphisms in genes.

Two different methods are described for inserting highly fluorescent peryleneimide chromophores into the scaffolding of polyphenylene dendrimers through iterative Diels-Alder cycoladditions. The results have shown that all dendrimers have good solubility in common organic solvents, high fluorescence quantum yields and defined distances between the chromophores, making them attractive candidates for single-molecule spectroscopy.

Ab initio vibrational self-consistent field (VSCF) calculations and time-resolved resonance Raman spectroscopy are used to examine the role of anharmonic effects in the vibrational spectroscopy of the dark state and two major chromophore intermediates of the photoactive yellow protein (PYP) photocycle. The results have shown the importance of the inclusion of anharmonicity in spectroscopic calculations and the sensitivity of experiments to anharmonicity.

Resonance Raman spectroscopy is combined with quantum chemical calculations to determine the chromophore structure in various states of phytochrome. A molecular model is derived for the photoinduced reaction cycle.

The infrared Raman spectra is described for the dark state of the bacterial photoreceptor containing a 4-hydroxycinnamyl chromophore, photoactive yellow protein (PYP), whose chromophore is isotopically labeled with [super 13]C at the carbonyl carbon atom or at the ring carbon atoms. The observations are presented and the complete study provides base for further research of the photocycle mechanism in PYP by vibrational spectroscopy.

The ATR-FTIR and UV/vis spectra of concentrated nitrate solutions are measured over a large concentration range to gain a better understanding of the nitrate ion chromophore in concentrated aqueous nitrate aerosols. It is found that both ATR-FTIR and UV/vis spectroscopy shows change in the nitrate ion spectra with increasing concentration.

An introduction to the generating function (GF) method was presented to show formalism applied to the field of single-molecule spectroscopy (SMS). It was suggested that continual evolution of experimental single-molecule techniques prescribed that new theories and computational algorithms be developed for the purpose of interpreting SMS measurements.

The synthesis of a new series of molecules composed of a ruthenium cation liganded by a chloro or a thiocyanato, a 4,4'-(diethoxycarbonyl)-2,2'-bipyridine, and a 2,2':6',2''-terpyridine substituted in its 4' position by a difluoroborazaindacene or a zinc phthalocyanine is described. The results show strong electronic coupling between the zinc phthalocyanine unit and the ruthenium complex but weakly electronically coupled systems in the case of dyads containing a difluoroborazaindacene unit

The excited-state dynamics of adenine and thymine dimers and the adenine-thymine base pair were investigated by femtosecond pump-probe ionization spectroscopy with excitation wavelengths of 250-272 nm. It was found that the excited state dynamics of the adenine (A)-thymine (T) base pair were similar to those of the homodimers and indicated a conserved relaxation mechanism in the two chromophores.

An 'X-shaped' 2D electrooptic (EO) chromophore with extended orthogonal conjugation was designed and synthesized. Self-assembled thin films of the chromophore were fabricated through a layer-by-layer chemisorptive siloxane based approach.

Three new azo-benzene-based push-pull chromophores with dendritic architecture are synthesized as active materials for electro-optic applications. These chromophores are synthesized in six or seven synthetic steps with an overall yield of around 80% per step and high purity.

Time-dependent density-functional theory (TDDFT) is applied to calculate one- and two-photon absorption spectra (related to linear and third-order optical responses, respectively) in a series of large donor-acceptor substituted conjugated molecules. It is concluded that the TDDFT approach is a numerically efficient method for quantitative calculations of resonant nonlinear polarizabilities in large organic chromophores.

It was found that the steady-state spectroscopy of pyrene chromophores bound to several interfaces points to extensive aggregation. Time-resolved measurements indicate that there was substantial coupling between the pyrene chromophone and conductive substrates.

A new technique to measure the direct degenerate two-photon-absorption (TPA) spectra is reported, which is based on using a single intense continuum beam with no need for any spectral scanning or wavelength tuning mechanism. In this approach, a prism or a grating spectrally disperses a powerful continuum beam.

The problems related with the familiar phenomenological Forster's method in which interaction strengths are derived from spectra of the interacting chromophores are analyzed. Three physically distinct ways in which refractive index affects the rate and suggest how they should be handled are distinguished in our analysis.

Steady-state and time-resolved fluorescence measurements are conducted on newly synthesized Frechet-type dendrimers with naphthalene peripheral groups in homogeneous and sodium dodecyl (SDS) micellar solutions. It is observed that geometry and conformation are very important qualities of a desired dendrimer for the study of photophysical properties of attached chromophores.

A preliminary investigation of the ultrafast relaxation dynamics and temperature-dependent fluorescence of the isolated chromophore of green fluorescent protein (GEP) is reported. The study concluded that the fluorescence intensity increases dramatically with decreasing temperature, with the main part of the increase occurring in the supercooled liquid, and continuing below the glass transition.

A systematic study of spectroscopy and dynamics of a chromophore attached at the interface between water and a self-assembled organic monolayer is presented. The slow components of water dynamics at the normal liquid/liquid interface are missing at the water/self-assembled monolayer interface.