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Four series of multiarmed chiral aryl ethers carrying two, three, five or eight side-chains on a variety of aromatic core molecules are synthesized and their conformation and dynamic behavior are examined. The conformers have interconverted either by synchronized aryl-aryl bond rotations or by concave-convex inversion of the corannulene moiety.

Photophysics and photochemistry of 2-anthracenecarboxylate (AC) bound to bovine serum albumin (BSA) are investigated. The largest photochirogenesis was observed for the site with moderate binding affinity showing that compensation between the strength of the binding and mobility is important to achieve chiral discrimination for biomolecular reactions in chiral environments.

Subsequent time-dependent DFT calculations with BH-LYP and B3-LYP functional were performed to obtain theoretical circular dichroism (CD) spectra. The results show the advantage of the DFT-D method for the geometry optimization of large systems with donor-acceptor interactions and the TD-DFT/BH-LYP calculations for reproducing the experimental CD spectra.

The conformations of inherently chiral resorc[4]arenes are studied by circular dichroism (CD) spectroscopy. Not only the conformation of the calixarene is dramatically manipulated by the solvent but also that the joint use of chiroptical measurements and theoretical calculations is a powerful and versatile tool for elucidating structural variations in supramolecular chemistry.

The complexation behavior, chiralty induction and inversion in the achiral host, a racemic mixture of ethane-bridged bis(zinc octaethylchlorin) and optical activity modulation in the chiral hosts, enantiopure upon interaction with chiral and achiral amine guests are investigated by means of the UV-vis CD, and (super 1H) NMR techniques and compared with the corresponding spectral data of the bis-porphyrin analogue. It was found that the chirogenesis pathway is strongly dependent upon the structures of both major components of the supramolecular systems.

Binding behavior of L-and D-trytophan-modified beta-cyclodextrins with four bile acids, which are cholate, deoxycholate, glycocholate and taurocholate, are investigated by fluorescence circular dichroism and 2D-NMR spectroscopies and fluorescence lifetime measurement. The combined use of the calorimetirc and NMR ROESY spectral examinations revealed the correlation between the thermodynamic parameters and the role of sidearm conformation in modified beta-cyclodextrins.

The zeolite interior is clearly able to enhance the power of a chiral auxiliary during reaction from excited singlet and triplet states are reported. The cations and confined space force the molecule to adopt a conformation, which results in a stronger interaction between the chiral center and the site of reaction present within a single molecule.

Photochemistry of optically pure trans-2,3-diphenyl-1-benzoylcyclopropane is examined in isotropic solution and within zeolites. The findings indicate that it isomerizes by cleavage of either the C(sub 1)-C(sub 2) or C(sub 1)-C(sub 3) bond.

Research has been conducted on the methanol's photosensitized addition to (R)-(+)-limonene. Results indicate that this addition has led to a highly diastereodifferentiating bimolecular asymmetric photoreaction.

Research has been conducted on the p-nitrobenzoyl-beta-cyclodextrin supramolecular complexes. The description of the photoinduced electron transfer system with the p-nitrobenzoyl-beta-cyclodextrin as acceptor and naphthalene as donor held together via the hydrophobic interactions is presented.

Research has been conducted on naphthalene-tethered resorcinol ethers. The results of the sequential photocycloaddition-rearrangement reactions of these ethers irradiated in the presence/absence of acid are reported.

Research has been conducted on the calix[4]arene-tethered mono- and bis(beta-cyclodextrin). The molecular recognition behavior of these compounds with the fluorescence dyes in the aqueous buffer solution has been investigated and the results are reported.

Research has been conducted on the cyclic peptides composed of dipeptide units with alternating natural-unnatural amino acid units. The design and synthesis of these peptides have been carried out via the unnatural amino acid and the results indicate that all cyclic peptides with different pore size, shape and lipophilicity form ion channels upon examination by the voltage clamp method.

Research elucidates the syntheses and molecular recognition pattern of organoselenium-bridged beta-cyclodextrin dimers. Data reveal that the bis(beta-cyclodextrin)s exhibit higher affinity to structurally similar dyes than native beta-cyclodextrin. Furthermore the recognition mechanism is based on the size/shape-fit and induced-fit concept criteria.

Research describes the synthesis and characterization of two new heteroatom-bridged bis(benzo-12-crown-4ehter)s and diselenides together with their silver-selectivities behavior and structure-selectivity relationship in the silver-ion-selective electrodes in terms of steric and electronic effects of the nitro groups.

A study concerning bis(beta-cyclodextrin)s synthesized from beta-cyclodextrin is presented. Experiments include the investigation of the inclusion complexation behavior.

Mono(6-(p-methoxyphenylseleno)-6-deoxy)-beta-cyclodextrin was synthesized and characterized by elemental analysis and mass, FT-IR and 1H NMR spectroscopy. The circular dichroism spectral titration method was used to determine the stability constants of the inclusion complexation of the novel cyclodextrin derivative and mono(6-(p-tolylseleno)-6-deoxyl)-beta-cyclodextrin with a series acyclic and cyclic alcohols in a phosphate buffer solution (pH7.20) at 25 degrees centigrade.

Research was conducted to examine the synthesis and the molecular recognition behavior of L-tryptophan-modified beta-cyclodextrin. Fluorescence and circular dichroism spectrometry and fluorescence lifetime measurement were performed with and without different alcohols as guest molecules. Results suggest that the modified beta-cyclodextrin can recognize minimal structural differences in the guest alcohols analyzed based on their size/shape, hydrophobicity and rigidity.

A thermodynamic experiment was conducted to evaluate the complexation of alkali metal ions with N-phenyl-aza-15-crown-5, N-octylaza-15-crown-5, N-benzylaza-15-crown-5, N-benzylaza-18-crown-6, N-benzylaza-21-crown-7, and N-benzylaza-24-crown-8 in methanol at 25 degrees centigrade. Results show that N-substituents are important in the complexation of alkali metal ions with a nondonating side-chain.

A series of [Beta]-cyclodextrin derivatives, carrying pyridinio (4-6), phosphonyl (7, 8), seleno (9-11), m- and p-picolinyl (12, 13), o-chloroanilino (16), 8-quinolyl (17), furfuryl (18), and 9-fluorenyl (19) moieties in the side chain, were newly synthesized, and their complexation behavior was assessed and discussed thermodynamically, using L-tryptophan and a few naphthalene derivatives as representative guests. Calorimetric titrations have been performed at 25.0 [degrees] C in buffered aqueous solution (pH 7.20) to give the complex stability constants and thermodynamic parameters for the 1:1 inclusion complexation of these guests with the native and modified [Alpha]-, [Beta]-, and/or [Gamma]-cyclodextrins (1-20). All of the chemical modifications to the primary side of cyclodextrins examined led to significant changes in complex stability and thermodynamic parameters, which are elucidated in terms of the conformational, electrostatic, hydrogen-bonding, and hydration effects. Thermodynamically, the inclusion complexation is mainly enthalpy-driven with a negative or minor positive entropic contribution, which in some cases determines the complex stability. The induced circular dichroism spectral analyses of these cyclodextrin derivatives indicated that the aromatic moiety in modified [Beta]-cyclodextrins (4-6, 9-19) only shallowly penetrates into the hydrophobic cavity of [Beta]-cyclodextrin, while the phenyl phosphate and fluorenyl moieties in 7 and 20 are embedded into the hydrophobic cavity of [Beta]-cyclodextrin because of the longer linking chain. Using all the thermodynamic data for a wide variety of cyclodextrin derivatives obtained in this and previous studies, the entropy changes (T[Delta]S) were plotted against the enthalpy changes ([Delta]H) to give an excellent linear relationship. The slope ([Alpha]) of 1.02 and an intercept (T[Delta][S.sub.0]) of 4.3 of the regression line indicate substantial conformational changes and extensive desolvation caused upon complexation, respectively.

The synthesis and characterization of beta-cyclodextrins bearing m-toluidinyl or (9-fluorenyl)alkenyl moeity are described. The inclusion complexation properties of the compounds with L/D-amino acids were determined by fluorescence spectroscopy. The results showed that the modified cyclodextrins can recognize the size, shape and chirality of he amino acids. These properties were discussed in terms of the size/shape-fit relationship between the host cavity and guest molecules.

2,3-Diphenyloxirane, 1,2-diphenyl- and 1,2-bis(4-methoxyphenyl)cyclopropanes undergo enantiodifferentiating photoisomerizations in polar and nonpolar solvents in the presence of chiral electron-accepting photosensitizers. The study shows that the products' optical purities (op), which may reach 10.4%, vary radically with solvent polarity, with polar and nonpolar solvents at times giving antipodal products. Analysis suggests the enantiodifferentiation taking place as the racemic substrate quenches the excited chiral sensitizer.

Triplex formation and high steric congestion provide a temperature-dependent route to photoproducts with high optical purities (op). The enantiocontrolled isomerization of cyclooctene from (Z) to (E) is achieved by sensitization with chiral benzene(poly)carboxylates. The bulky carboxylates with their electron-donating groups are able to provide up to 68% op at -89 degrees Celsius and up to 50% op at ambient temperatures. The role of entropy in enantiodifferentiation is traced to structural dynamics of the exciplex.

Chiral polyalkyl benzenepolycarboxylates serve well as enantiodifferentiating singlet sensitizers in the photoisomerization of cyclooctene. The photostudy shows that the sensitizer forms a singlet exciplex, within which the favored reaction takes place via the rotational relaxation of 2-cyclooctene from planar to twisted singlet. Quenching by (E)-cyclooctene is not so favored but is controlled more by the diffusion rate. The unequal response to temperature variations also enhances enantiodifferentiation. The results open new photochemical routes with optical yields as high as 53%.

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 mechanisms associated with the supramolecular complexation and enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid with 4-aminoprolinol derivatives are discussed. A new protocol for determining the mechanism of photochirogenesis of the system is also explained.

The studies on the self-inclusion behavior of a sensitizing host have showed that the appended naphthalene moiety of 6-(5-cyanonaphthyl-1-carboamido)-6-deoxy-[beta]-cyclodextrin has perched laterally on the cyclodextrin rim in aqueous methanol but is shallowly included and tilted in its own cavity in water. The compensation plot of the differential activation enthalpy versus entropy has given an excellent straight line for water adduct but an unprecedented bent plot for methanol adduct, indicating a switching of the mechanism in methanol solution.

The synthesis of a series of 6-O-benzoyl-[beta]-cyclodextrins with methyl, methoxy, methoxycarbonyl, and bromo substituent(s) at the ortho-, meta-, and/or para-position(s) are reported. The compounds could be used as chiral sensitizing hosts for supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene to its chiral (E)-isomer.

The article explains the mechanisms that are involved in the supramolecular enantiodifferentiation of the photocyclodimerization of 2-anthracenecarboxylic acid (AC), which is mediated by the capped [gamma]-cyclodextrins. The rigidity of the cap is shown to highly control the enantioselectivity of the system.

The dynamic behavior of new CT-dyads (CT = charge transfer) is studied by using ultraviolet (UV)-vis, fluorescence and NMR spectroscopies under a variety of conditions. The results have shown that the conformational fixation of CT-dyads is a conventional tool for manipulating the chiroptical properties of the CT transition, which is applicable in general to different molecular and supramolecular CT systems.

A series of secondary-face-substituted and skeleton-modified gamma-cyclodextrins (gamma-CDs) are prepared as chiral hosts for enantiodifferentiating [4+4] photocyclodimerization reactions of 2-anthracenecarboxylic acid (AC). The influence of temperature and high pressure on the supramolecular photochirogenic reaction is investigated.

Effective supramolecular chirogenesis in the achiral bis-porphyrin host upon noncovalent interactions with bidentate, chiral guests containing amino/hydroxyl groups, which are able to coordinate to the central zinc ion of the porphyrin, is demonstrated. The results give a better understanding of total mechanism of supramolecular chirogenesis in natural and artificial systems.

Research has been conducted on gamma-cyclodextrins. The authors report that the stability constants, free enertgy, enthalpy and entropy changes for gamma-cyclodextrins' complexation with enantiomeric and diastereomeric N-acetyl- and N-carbobenzyloxy-dipeptides possessing aromatic moieties have been determined in aqueous buffer solution via the use of titration microcalorimetry.

Research has been conducted on (beta-cyclodextrin). The stnthesis on this compound and its binding behavior with sreroids have been carrried out in investigating the cooperative co-inclusionn of guests and the tether by cyclodextrin moieties, and the results sre reported.

Research has been conducted on mono-, bis- and tris-cyclodextrins. The authors describe the synthesis of these compounds with phosphoryl tethers, and report their thermodynamic behavior with neutral and negatively charged alicyclic guests investigated via microcalorimetric titration.

Supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to the chiral (E)-isomer (1E) via inclusion and sensitization by modified alpha-, beta-, and/or gama-cyclodextrin derivatives, possessing benzoate (2a, 3a, 4a), isomeric phthalates (3b-d), and tethered benzamide (3e) chromophores, is studied in aqueous methanol solutions at varying temperatures. Results reveal that the modification of cyclodextrin with a sensitizing group successfully enhanced the product through the excited-state supramolecular interaction within the cavity. Study also reveals that the entropy factor does not appear to play a vital role in the supramolecular photochirogenic process.

Lariat ethers, namely crown ethers with additional donor atom(s) in the side arm(s), is designed and synthesized in order to alter the cation binding ability and selectivity of the parent crown ethers through further ligation of the side arm donor(s) to a cation accommodated in the crown cavity. Thermodynamically, the complexation of lanthanoid perchlorates with parent benzo-15-crown-5 is absolutely entropy-driven in acetonitrile, while the complexation of lanthanoid nitrates withbenzo-15-crown-5 derivatives is primarily driven by exothermic enthalpy changes with accompanying moderate entropic gain or small entropic loss.