Electrochemical control of the structure of two-dimensional supramolecular organization consisting of phthalocyanine and porphyrin on a gold single-crystal surface

Two-component adlayers consisting of cobalt(II) phthalocyanine (CoPc) and a metalloporphyrin such as 5,10,15,20-tetraphenyl-21H,23H-porphine copper(II) (CuTPP), 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine copper(II) (CuOEP), or 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (CoTPP) were prepared by immersing either an Au(111) or Au(100) substrate in a benzene solution containing those molecules. The mixed adlayers thus prepared were investigated in 0.1 M HClO4 by cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM). The composition of the mixed adlayer consisting of CoPc and CuTPP molecules was found to vary with immersion time. CoPc molecules displaced CuTPP molecules during the modification process with increasing immersion time, and the CuTPP molecules were completely displaced by CoPc molecules in the mixed solution after a prolonged modification time, during which the underlying Au(100) substrate underwent phase transition from the reconstructed (hex) lattice to the unreconstructed (1 x 1) lattice. The two-component adlayer of CoPc and CuTPP was found to form a supramolecular adlayer with the constituent molecules arranged alternately on Au(100)-(hex). The striped structure was stable on Au(100)-(hex) at or near the open circuit potential (OCP), whereas the mixed adlayer was disordered on Au(100)-(1 x 1) at potentials more positive than OCP, where the phase transition of the arrangement of underlying Au atoms (i.e., the lifting of reconstruction) was induced electrochemically. A similar two-component supramolecular adlayer consisting of CoPc and CuTPP was formed on Au(111). A highly ordered, compositionally disordered adlayer of CoTPP and CuTPP was formed on Au(100)-(hex), suggesting that the adlayer structure is independent of the coordinated central metal ion for the formation of supramolecular nanostructures composed of those molecules. A supramolecular organization of CoPc and CuOEP was also found on Au(111). The surface mobility and the molecular reorganization of CoPc and CuOEP on Au(111) were tuned by modulation of the electrode potential. It is concluded that molecular assemblies of the two-component structure consisting of phthalocyanine and porphyrin were controlled not only by the crystallographic orientation of Au but also by the modulation of electrochemical potential.     

Formation of highly ordered porphyrin adlayers induced by electrochemical potential modulation

Molecular self-assembly of porphyrin derivatives formed with intermolecular hydrogen bonding on the surface of Au(111) electrode in acidic solution can be controlled by varying the number of peripheral carboxy groups and the applied electrochemical potential.     

A novel dual antagonist of thromboxane A2 and leukotriene D4 receptors: synthesis and structure-activity relationships of chloroquinolylvinyl derivatives

To discover an orally active thromboxane A(2) (TXA(2)) and leukotriene D(4) (LTD(4)) dual antagonist, we designed and synthesized chloroquinolylvinyl derivatives based on the structures of the TXA(2) antagonist daltroban and the LTD(4) antagonist montelukast. Among these derivatives, 4-{[(2-(4-chlorophenylsulfonylamino)-1-{3-[(E)-2-(7-chloro-2-quinolyl)vinyl]phenyl}ethyl)thio]methyl}benzoic acid (18d) showed potent inhibitory activity against U46619-induced aggregation of guinea pig platelets and LTD(4)-induced contraction in the guinea pig ileum, with IC(50) values of 340 nm and 0.40 nm, respectively. Oral administration of 18 d also inhibited both the LTD(4)-induced acceleration of plasma leakage to skin in guinea pig and the U46619-induced increase in airway resistance in guinea pig with ED(50) values of 0.47 mg/kg and 3.3 mg/kg, respectively.     

Fully fused boron-doped polycyclic aromatic hydrocarbons: their synthesis,structure–property relationships,and self-assembly behavior in aqueous media

Planarized triarylboranes are attracting increasing attention not only as models of boron-doped graphenes, but also as promising materials for organic optoelectronics. In particular, polycyclic aromatic hydrocarbon (PAH) skeletons with embedded boron atom(s) in the inner positions are of importance in light of their high chemical stability and π-stacking ability derived from their planar geometries. Herein, we disclose a robust synthesis of such fully fused boron-doped PAHs and their self-assembly behavior in aqueous media to explore their potential utility in biological applications. The synthesis using in situ-generated planar diarylboranes as a key precursor afforded a series of fully fused boron-doped PAHs, even including an amphiphilic derivative with hydrophilic side chains. These compounds exhibited red emission in solution, and slight structural modification resulted in increased fluorescence brightness. While these compounds showed relatively low Lewis acidity compared to their partially ring-fused counterparts, their Lewis acidities were slightly increased in polar solvents compared to those in nonpolar solvents. In addition, their B–N Lewis acid–base adducts, even those with a strong, charge-neutral Lewis base such as N,N-dimethylaminopyridine (DMAP), exhibited photo-dissociation behavior in the excited state. The amphiphilic derivative showed significant spectral changes with increased water content in DMSO/H₂O mixed media and formed sheet-like aggregates. The disassembly and assembly processes of the aggregates were externally controlled by the addition of DMAP and an acid, accompanied by a change in the fluorescence intensity.

A series of fully fused boron-doped polycyclic aromatic hydrocarbons is synthesized. Self-assembly of an amphiphilic derivative can be controlled by addition of a Lewis base or an acid in aqueous media.     

Synthesis and antiviral activities of some 4,4'- and 2,2'-dihydroxytriphenylmethanes

We synthesized some 4,4'- and 2,2'-dihydroxytriphenylmethane derivatives 3a--e and 4a--c by condensation of phenol 1 and aromatic aldehyde 2 in moderate to good yields (30--83%). Most of them showed significant antiviral activity against herpes simplex virus type 1 (anti-HSV-1 activity) in a plaque reduction assay. The most potent antiviral activity (EC(50)=0.79 microg/ml) was observed in the 4,4'-dihydroxytriphenylmethane derivative 3b. This compound 3b showed lower cytotoxicity (CC(50)=30.2 microg/ml), compared to that of the prototype 3a.     

A new lignan glycoside and phenylethanoid glycosides from Strobilanthes cusia BREMEK

The root of Strobilanthes cusia BREMEK. (Acanthaceae), popularly known as Da-Ching-Yeh, has been commonly used in traditional Chinese medicine. It is used to treat influenza, epidemic cerebrospinal meningitis, encephalitis B, viral pneumonia, mumps, and severe acute respiratory syndrome (SARS). In this study, we found a new lignan glycoside (6) and two new phenylethanoid glycosides (7, 8) together with five known compounds as chemical constituents of Strobilanthes cusia root. Some samples were examined for anti-herpes simplex virus type-1 (HSV-1) activity. Among the tested samples, lupeol showed anti-HSV-1 activity (EC(50): 11.7 microM) and showed 100% inhibition of virus plaque formation at 58.7 microM.     

Synthesis of 2,2'-dihydroxybisphenols and antiviral activity of some bisphenol derivatives

New diphenylmethane-type 2,2'-dihydroxybisphenols (5a-d) were prepared regioselectively in good yields. We evaluated the antiviral activity of some bisphenol derivatives synthesized by the plaque reduction assay. Most of the compounds showed significant antiviral activity and the 4,4'-dihydroxybisphenol derivative (10) showed higher activity than 2,2'-bisphenol derivatives. This compound had EC50 value of 1.8 microg/ml.     

Synthesis of Boronate‐Based Benzo[fg]tetracene and Benzo[hi]hexacene via Demethylative Direct Borylation

A demethylative direct borylation is reported, which was applied to the synthesis of benzo[fg]tetracenes containing boronate ester, amide, and thioester substructures. Depending on the heteroatom adjacent to boron, the molecules showed characteristic photophysical properties, molecular arrangements, and chemical stabilities. The key to the successful synthesis is the appropriate choice of the boron source and Brønsted base. The versatility of the direct borylation was demonstrated by the synthesis of a boronate‐based benzo[hi]hexacene.