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Four donor-acceptor [2]catenanes with cyclobis(paraquat-p-phenylene) are synthesized under mild conditions by using [Cu.sup.+]-catalyzed Huisgen 1,3-dipolar cycloaddition and [Cu.sup.2+]-mediated Eglinton coupling in the final steps of their syntheses. The analysis has shown that the values of barrier height decrease with the increasing size of the [pi]-electron-donating macrocycle and tend to be lower in the sterically less encumbered series of [2]catenanes containing the 1,3-butadiyne moiety.

The specific use of a functionalized sapphyrin diol is presented, which yields stable water-suspendable nanotubes and also allows the formation of well-defined assemblies in ionic liquids. The findings reveal that water-suspendable nanotube-sapphyrin complexes are formed from the functionalized sapphyrin derivative.

The synthesis and characterization of a new series of relatively flexible cofacial donor-acceptor dyads for singlet-singlet energy transfer with the corrole or etio-porphyrin free base and zinc porphyrin is described, as the acceptor and donor. The results show that the presence of a bulky group located between the acceptor and the donor moiety influences the energy transfer rate.

A series of donor-acceptor p-nitro-p'-alkoxy (OR) substituted (E,E,E)-1,6-diphenyl-1,3,5-hexatrienes were prepared and their properties and crystal structures investigated. The flouresence spectra of these crystals were red-shifted relative to those for the solutions in low polar solvents, which can be attributed to the planarization of molecules in the solid state and to the strong intermolecular interactions in crystals.

The electronic structure and charge transfer characteristics of two structural isomers of donor-acceptor substituted sesquifulvalene are studied by using a sufficiently high level of ab initio quantum mechanical methods. Since the chosen molecules are polar and only the dominant solute-solvent electrostatic interaction is considered, the variation of their rotational energy barriers and transition energies in solution can be interpreted and distinguished from each other in terms of the polarity difference between the ground and excited states.

Organic (CNT)-inorganic (CdTe) nanohybrids were systematically devised and tested as donor-acceptor nanohybrids in dilute condensed media and as integrative components at electrode surfaces. The novel nanohybrids were characterized both in the ground and excited states with specific accent on electron-transfer chemistry.

A new methodology for [n +1] radical annulation using sulfur dioxide as a geminal radical acceptor/ donor is presented. This methodology provides a novel route to the formation of five-, six-, and seven-membered cyclic sulfones utilizing a radical chain mechanism under very mild conditions.

The 12CaO.7Al(sub 2)O(sub 3) (C12A7) crystal with a nanoporous lattice framework exhibits high electrical conductivity with activation energy of approximately 1.5 eV when equilibrated in a hydrogen atmosphere above approximately 800 degree Celsius. The study reveals that the H(super -)ion in C12A7 acts as a two-electron donor through conversion of H(super -) to H(super +).

Correlated MP2 and MCSCF MO calculations of several model push - pull ethenes in most cases indicates no great participation of excited singlet and triplet electronic configurations in either the minima or the transition structures for the suggested facilitated intramolecular rotation about the polarized C=C bond. This situation changes significantly only in molecules with sulfur atoms in the molecules as either donors or acceptors.

The synthesis of three novel narrow HOMO-LUMO gap heterocyclic mixed trimers containing a o-quinoid electro-acceptor thienopyrazine central moeity endowed by two donor 3,4-ethylenedioxy-2-thienyl (EDOT) units and with different patterns of hexyl functionalization is reported. It is concluded that these trimers are potential candidates for obtaining polymers with significant low energy gap combining electroactivity.

Computational studies were conducted to compare the extent of substituent influence on the vertical electron affinities (EAs) and ionization energies (IEs) of 43 substituted tria-, penta-, and heptafulvenes with those of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as representing strong electron-acceptor and -donor compounds. The findings for the properties of compounds composed of a donor-type heptafulvene fused with an acceptor-type pentafulvene revealed the route to design bis(fulvene)s so that the IE and EA of the two separate fulvene segments are retained, allowing for the design of compact donor-acceptor dyads.

Time-resolved spectroscopy is used for comparing the photoinitiated charge separation (CS) and recombination (CR) in a series of donor-bridge-acceptor (D-B-A) molecules with cross-conjugated, linearly conjugated and saturated bridges. Molecular conductance calculations on the bridges have shown that cross-conjugation has resulted in quantum interference effects that have altered the through-bridge donor-acceptor electronic coupling as a function of charge injection energy.

The distance- and temperature-dependent rate constants are measured for charge separation in capped hairpins in which a stilbene hole acceptor and hole donor are separated by [A.sub.3][G.sub.n] diblock polypurine sequences consisting of 3 adenines and 1-19 guanines. The longer diblock systems have obeyed the simplest model for an unbiased random walk, which has provided a direct measurement of [k.sub.hop] for a single reversible G-to-G hole hopping step.

The efficient synthesis and photophysical properties of a series of ambipolar donor-acceptor-donor systems is described where the acceptor is dibenzothiophene S,S-dioxide and the donor is fluorene, carbazole, or arylamine. The emission properties could be effectively tuned by systematically changing the position of substitution on both donor and acceptor units (which influences the extent of conjugation) and the redox potentials of the donor units.

An extensive and detailed theoretical analysis of the electron charge displacement accompanying the interaction, over several crucial sections of the potential energy surface (PES) was performed to demonstrate that the water-H2 interaction is accompanied by charge transfer (CT) and that the observed stabilization energy correlates quantitatively with CT magnitude at all distances. CT is found to be a significant and strongl stereospecific component of the water-H2 interaction chemistry, with water functioning as electron donor or acceptor in different orientations.

Transient optical studies of films comprising regioregular poly(3-hexylthiophene) (P3HT) blended with a series of perylene-3,4:9,10-tetracarboxydiimide (PDI) electron acceptors are conducted to understand the role of interfacial energetics in influencing the separation of charge transfer states into dissociated charge carriers in organic donor/acceptor blend films. The close correlations observed between the PDI electron affinity and the efficiency of charge separation are explained in terms of studies of charge photogeneration for other organic donor/acceptor blend films, including other polymers, blend compositions.

The synthesis, structure, redox and photophysical properties of the two- and three-layered donor-acceptor (D-A) type [3.3]paracyclophanes ([3.3]PCPs) are presented. The (p-ethylbenzenesulfonyl)methyl isocyanide coupling method is used for achieving the synthesis of the two- and three-layered [3.3]PCPs containing 2,1,3-benzothiadiazole (BTD) as an acceptor.

Protonation-induced intramolecular cyclization reactions of new donor (D)-acceptor (A) and D-A-D conjugated molecules 1-triarylaminoethynylanthraquinone and 1,5-bis(triarylaminoethynyl)anthraquinone is reported. The obtained condensed-ring compounds showed unique optical, electrochemical, and magnetic properties due to the extremely narrow HOMO-LUMO gap.

The Paterno-Buchi reaction of chiral p-cyanobenzoates with 1,1-diphenylethene has shown that the excited charge-transfer (CT) complex formed upon selective excitation at the CT band is different in structure and reactivity from the conventional exciplex generated through the direct excitation of acceptor. The combined use of irradiation wavelength, temperature and solvent has provided with a convenient, powerful tool not only for analyzing the mechanistic details of photoreaction but also for critically controlling the stereochemical outcomes of photochirogenic reaction.

The various effects of the donor-acceptor distance and the isotope effects on the force constant exhibited during barrier compression in the H-tunneling reactions are analyzed. The force constant is shown to highly increase with a decrease in the donor-acceptor relationship of the system.

Lanthanide (Ln) tags are applied in the analysis of the 65 kDa membrane-associated protein complex formed by the electron carrier adrenodoxin and its electron donor, adrenodoxin reductase in order to determine whether enough restraints can be retrieved for proteins with low solubility and availability. The studies have shown that with the application of Ln tags paramagnetic NMR restraints for structure determination can be retrieved for difficult, low-concentration protein complexes.

The nucleophilicity values of the commonly used arenes and heteroarenes are calculated by using the inverse concept of electrophilicity and nucleophilicity and with four different available equations for electrophilicity and electrodonating power. Four different arene and heteroarene series are subjected to local nucleophilicity analysis in order to predict the site selectivity in electrophilic aromatic substitution reactions (EAS).

The impact of intramolecular noncovalent interaction, H-bonding and Li-bonding, on the properties of substituents communicating through the resonance effect in such molecular systems as salicylaldehyde, o-hydroxy Schiff base, o-nitrosophenol and their lithium analogues is examined. The studies have shown that the relation between intramolecular noncovalent interactions and the [pi]-electron delocalization in the sequence of [pi]-conjugated covalent bonds linking A and B is considered in terms of the Hammett-like substituent effect in which electron-donating and electron-withdrawing properties of substituents are affected by the noncovalent interaction.

The versatile application of [Ce.sub.2]@[I.sub.h]-[C.sub.80] building block for synthesizing a novel electron donor-acceptor conjugate, [Ce.sub.2]@[I.sub.h]-[C.sub.80]-ZnP is described. The strongly exothermic [([Ce.sub.2]@[I.sub.h]-[C.sub.80]).sup.*-]-[(ZnP).sup.*+] radical ion pair state formation could be compensated within the framework of a nonadiabatic charge transfer by a [C.sub.80.sup.6-]/ZnP electronic matrix element, as the sum of good overlap and short distance, that exceeds that for [[[Ce.sub.2]].sup.6+]/ZnP.

A study was conducted to demonstrate the electron-deficient aromatic box formed by the appropriate combination of electron-donating (D) and accepting (A) guest pairs to result in an asymmetric quadruple A-D-A-A stacking sequence quantitatively. The results offer insight into the inner D-A guest pair which rapidly swaps their positions to create a dynamic aromatic array and the swift guest motion that largely depends on the donor aromatics.

Well-defined star-shaped donor-[pi]-acceptor meta-conjugated systems with broad absorption features are prepared by facile synthetic routes, in which triphenylamine (TPA) moiety as an electron donor and 2-dicyanomethylen-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) unit as an electron acceptor are introduced in various ratios. The steady and transient emission spectra have displayed that these compounds possess an intramolecular energy transfer in a meta-conjugation system and the structural variation has helped in understanding the tuning strategy of optical properties in D-[pi]-A-systems.

The self-assembly of the nanofibers with built-in donor/acceptor heterojunction upon admission of MeOH, the enantiomerically pure form of chiral amphiphilic porphyrin-fullerene dyad in presence of C[H.sub.2][Cl.sub.2] is reported. The electron and hole mobilities under zero electric field estimated from time-of-flight profiles are comparable to those reported for top-class organic materials with a donor/acceptor heterojunction.

The first Au(I)-mediated C-H activation of arenes is described and Au(I) salts have undergone C-H activation with electron-poor arenes, in contrast to Au(III) salts, which has activated electron-rich arenes. The highly regioselective process has occurred under very mild conditions and has given access to a variety of Au(I)-arene complexes in excellent yields.

Three new carbazole-based fluorescent boronic acid sensors were synthesized to study the fluorescence transduction efficiency of the novel d-PET effect. The orientation of the electron donor/acceptor that might significantly affect the fluorescence modulation efficiency of the PET effect could be applied for future design of PET sensors with improved fluorescence transduction efficiencies.

A one-donor/three-acceptor multicolor time-resolved fluorescence energy transfer (TR-FRET) system is developed and its use is exemplified by monitoring a ligand-regulated protein-protein exchange process in a four-component biological system. The studies have shown the power of a four-color TR-FRET experiment and have also shown that the overall process of estrogen receptor ligand exchange and coactivator binding is a dynamic but precisely coordinated process.

The synthesis and aggregation properties of a series of differently substituted star-shaped hexaaryltriindoles both in solution and in the solid state are reported. The strength and geometry of the stacking tendency which contrasted with the trend expected for an aggregation induced solely by [pi]-[pi] interactions that are influenced by the substituents could be explained by considering an important contribution of multiple cooperative CH-[pi] interactions.

The development of an effective [Rh.sub.2][(S-DOSP).sub.4]-catalyzed asymmetric cyclopentannulation of indolyl rings is reported. The study results demonstrated that rhodium-catalyzed reactions of donor/acceptor carbenoids which proceed by means of zwitterionic intermediates could be carried out with very high asymmetric induction.

Efficient performance requires well-controlled segregation of electron donor and acceptor moieties, which is achieved by using block copolymers of tetraphenylporphinatozinc(II) (donor) and [C.sub.60] fullerene (acceptor) using living ring-opening metathesis polymerization (ROMP). Thin films of the self-assembled nanophase-segregated copolymers have displayed high charge carrier mobilities and electrical conductivities as well as highly repeatable photocurrent switching with rapid ON/OFF responses upon white light irradiation.

Phenyleneethynylene-based conjugated copolymers by using benzo[1,2-d:4,5-d']bis[1,3]dioxole (BDO) in the repeating unit are described. The very large Stokes shifts of the monomers, which are due to the small oscillator strength of the lowest optical transition, are retained in the polymers due to covalently dihedral angles in the substituents.