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The compound [Re.sub.2][(hpp).sub.4]F[(TFPB).sub.2] is characterized by both X-ray and neutron diffraction and an EPR spectroscopy of [Re.sub.2][(hpp).sub.4][Cl.sub.2]P[F.sub.6] at multifrequency (9-95 GHz) is studied by using dilute solution, frozen glass and neat powder samples. It is indicated that the unpaired electron in a [Re.sub.2.sup.7+] compound resides in a dominantly metal-based orbital.

Batzelladine F was synthesized in enantioselective and stereoselective fashion in 15 steps. Also disclosed is the use of a chemical synthesis of complex guanidine alkaloids to prepare four stereoisomers of the presumed structure of batzelladine F.

The synthesis and structural characterization of a series of tungsten guanidinate and amidinate complexes derived from the series of Cl(sub 4)(RCN)W(N'Pr),Cl(sub 4)(RCN)W(NPh), and Cl(sub 4)(RCN)W(NC(sub 3)H(sub 5)) compounds are described. It is demonstrated that titanium guanidinate complexes can serve as precursors for the chemical vapor deposition of titanium carbonitride and tantalum guanidinate complexes yield TaN by chemical vapor deposition.

Cyclic and acyclic guanidinium-based salts are synthesized with the help of the quarternization of guanidine derivatives with nitric or perchloric acid or with iodomethane followed by metathesis reaction with silver nitrate, silver perchlorate, or ammonium dinitroamide. Most of the salts exhibited low melting points and good thermal stabilities.

The methylene-linked bicyclic guanidine based on the 1,3,4,6,7,8-hexahydro-2H-pyrimidol[1,2-a]pyrimidine (hppH) framework provides a versatile platform able to support trigonal-planar, tetrahedral, and square-planar metal centers.

The crystal structure of the closed preinsertion complex is described for the Y567A mutant with dATP opposite a templating guanidinohydantoin (Gh) (R-configuration) in a 13/18mer primer-template (P/T). The studies have shown that Gh is rejected as a templating base by wt RB69pol because G568 is inflexible, preventing Gh from pairing with the incoming dATP or dGTP base.

The article presents a complete analysis of the various conformations, conformational preferences and conformational exchange taking place in the N' -substituted N-acylguanidines. The conformational preferences are shown to be highly dependent on the strength and number of the various intermolecular interactions.

A new type of [C.sub.2]-symmetric chiral bisguanidine is designed as a very efficient catalyst in the inverse-electron-demand hetero-Diels-Alder reaction of chalcones with azlactones. Hydrogen bonds are vital for the activation and stereoinduction of the reactions and in all cases, the major is HAD adducts, which are obtained as a single diastereomer along with little amount of Michael addition products.

The ability of the guanidinylating reagent N' ,N' -diBoc-N-triflyl-guanidine (GN-Tf) to react with in situ formed free amines from azides in carbohydrates scaffolds is analyzed. This reaction method has helped in preparing guanidine derivatives in a one-pot manner, either with primary or secondary azides with different substitution patterns.

The article presents a new direct asymmetric aldol reaction, which uses the chiral bicyclic guanidines as catalysts for the conversion of the 5H-oxazol-4-one complexes. The reaction is shown to be extremely enantioselective and smooth.

The article explains the syntheses, properties and reactivity of a new series of mixed-ligand titanium guanidinates. The surface chemistry and the applicability of the compounds to be used as potential atomic layer deposition precursors are also discussed.

An unusual Michael addition between 2-aryl-substituted acrylates and 3,3-dimethoxypropanenitrile which forms a 4-methoxymethylene-substituted 4-cyanobutyric ester or to a 4-dimethoxymethyl 4-cyanobutyric ester, depending on the reaction temperature is described. The obtained compounds could be subsequently converted to 4-unsubstituted pyrido[2,3-d]pyrimidines upon treatment with a guanidine system under microwave irradiation.

The application of bicyclic guanidine 1,5,7- triazabicyclo[4.4.0]dec-5-ene (TBD) as an effective organocatalyst for the synthesis of amides from esters and primary amines is demonstrated. Theoretical and mechanistic studies offer insight into the higher reactivity of TBD due to both higher basicity and nucleophilicity than 1,4,6-triazabicyclo[3.3.0]oct-4-ene (TBO) as well as the high reactivity of the acyl-TBD intermediate, which is sterically prevented from adopting a planar amide structure.

The bis-guanidino compound [H.sub.2]C[{hpp}.sub.2] (hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) is converted to the monocation and isolated as the chloride and tetraphenylborate salts. Triadic analysis has shown that the dominant term causing the high basicity is the relaxation energy.

Highly reactive abasic site-(AP site)-detecting probes are constructed by introducing a hydrophobic and a hydrophilic residue in an aminooxy group. The guanidine residue has contributed to the solubility of the molecules in aqueous media and the biotinylated probes have provided more sensitive detection of AP sites in gemonic DNA than the conventional aldehyde-reactive probe.

The application of ytterbium triflate as an efficient catalyst for addition of amines to carbodiimides to N,N',N'-trisubstituted guanidines is described. The reaction is demonstrated the wide scope of amines under solvent-free condition.

Solid-state NMR was used to study the structure and lipid interaction of two cationic residues, [Arg.sub.10] and [Lys.sub.13], in the cell-penetrating peptide (CPP) penetratin. The data obtained from solid-state NMR confirmed the existance of guanidinium-phosphate interactions in penetratin and also confirmed stronger structural role of guanidinium groups than ammonium groups in the lipid-assisted translocation of CPPs across liquid-crystalline cell membranes.

A time-resolved fluorescence resonance energy transfer (tr-FRET) study is conducted to explain the characterization of the B domain of protein A (BDPA) during the process of chemical denaturation. BDPA is shown to exhibit a two-state folding mechanism, which helps in stabilizing the ensemble of different molecules at the time of denaturation.

A new trialkoxysilylated ionic liquid is prepared, based on disilylated guanidinium and monosilylated sulfonamide species, along with MCM-41 and SBA-15 related solids. The compound has helped in the preparation of new periodic mesoporous organosilicas containing covalently anchored ion-pair through both organo-cationic and organo-anionic moieties.

A flexible oligo(oxyethylene) spacer is used to develop a new class of molecular glues Asn[(TEG-[Gu.sup.+]).sub.9] and Gl[([Gu.sup.+]).sub.9]R having multiple guanidinium ions as sticky pendants. A multivalent salt-bridge formed between the sticky [Gu.sup.+] pendants and oxyanionic groups in proteins contributed to stabilization of protein assemblies in aqueous buffers.

Heteronuclear NMR spectroscopy is used for characterizing guanidine hydrochloride-unfolded apoflavodoxin at the residue level. Conformational preorganization in the unfolded state of an [alpha]-[beta] parallel-type protein has promoted off-pathway species formation.

The changes in the surface structure of lysozyme adsorbed at the air-water interface produced by the chemical denaturant guanidinium chloride are examined. The methodologies to predict the protein orientation at the interface, based on amino acid residues' surface affinities and charge, are validated.

The structure-property relationships of guanidinium ethoxysulfonate, [[C[(N[H.sub.2]).sub.3].sup.+][[[C.sub.2][H.sub.5]O-S[O.sub.3]].sup.-] that crystallizes in two polymorphic forms, both stable in a wide temperature range is described. Both crystals were observed to undergo structural phase transitions due to two-dimensional networks of hydrogen bonds, but polymorph II showed ferroelectric order in the low-temperature phase.

The optical resolution of (+/-)-1,2-bis(2-methylphenyl)ethylene-1,2-diamine as a chiral framework for 2-iminoimidazolidine with 2-methylphenyl pendant at 4,5-position is described. Addition of methyl group on the phenyl pendant of the guanidine improved its reactivity as a catalyst for asymmetric Michael reaction of tert-butyl diphenyliminoacetate and ethyl acrylate.

The effects of stabilizing sulfate salts, the denaturing chloride salt of guanidinium ([Gdm.sup.+]) and the neutral salt [Gdm.sub.2]S[O.sub.4] on many partially folded polypeptides are examined. One class of peptides have fulfilled the criteria of high [Gdm.sup.+] sensitivity and insensitivity to sulfate and the solute effects on each of the peptides are interpreted in terms of a key role for ion association in concentrated aqueous solution.

The article explains the architectural diversity and elastic networks present in different hydrogen-bonded host frameworks. The guest molecules with different shapes are found to lead to formation of different combinations.

The insertion of carbodiimides into amides is a useful method for the synthesis of guanidines and experimental evidence is provided for the corresponding reverse reaction. Guanidinates are not inert ligands in certain cases that can undergo C-N bond cleavage to form carbodiimides and amido units.

The synthesis of the guanidine analogue of the anticancer active 9-aminoacridine derivative ACRAMTU resulted in formation of two novel structural motifs of the acridine C9-N9 linkage.

X-ray crystallography and site-directed mutagenesis were used to study the bifunctional catalysis of proton transfer at an antibody active site. Results show that a correctly designed hapten can successfully extract multiple functional groups within an antibody and its ability to coordinate proton abstraction.

The DNA binding and condensation properties of guanidinium calixarenes are investigated and correlated with their cell transfection ability by using a combination of spectroscopic techniques and direct visualization by atomic force microscopy (AFM). The results indicate that relatively small variations in size, lipophilicity, and conformation of these water-soluble compounds, together with a subtle interplay between hydrophobic and electrostatic supra-molecular interactions, significantly affect the outcome of DNA condensation and cell transfection.

The structural and thermodynamic properties of the mutagenic 5-guanidino-4-nitroimidazole (NI) are elucidated by investigating the structure of the modified base itself and the NI-containing nucleoside with high-level quantum mechanical calculations. The results have suggested that the nonplanar NI lesion can adopt both syn and anti conformations with the specific preference depending on the partner base and the unique hydrogen properties have played a vital role in the distinct structural features of this unusual lesion.

Change of global structure as a function of concentration of a denaturant, guanidine hydrochloride is studied the laser-induced transient grating (TG) method for carboxymyoglobin (MbCO). The smaller diffusion coefficient of unfolded MbCO compared to folded MbCO can be interpreted in terms of changes of the protein-water interaction and the surface roughness of the protein, which is due to the conformational change of the protein from the native to the unfolding state.

A number of mimics for Cu,Zn-superoxide dismutase (Cu,Zn-SOD) are reported to study structural factors on the origin of the highly efficient superoxide dismutation mechanism. The positive guanidinium plays an important role for enhancing the SOD activity by guiding that superoxide to enter and peroxide to leave rapidly from the copper ion.

The hydrogen-bond-mediated construction of two premeditated anionic rosette-layer architectures using guanidinium and ubiquitous C3-symmetric oxoanions that carry unequal charges, such as guanidinium-carbonate I and guanidinium-trimesate II, is described. The present anionic rosette networks expand the scope of de novo engineering of charge-assisted hydrogen-bonded networks using ionic modular components, from which discrete molecular aggregates bearing the rosette motif might be derived.