Search

New cis -(1,2-azole)-aquo bis(2,2'-bipyridyl)ruthenium(II) (1,2-azole (az*H) = pzH (pyrazole), dmpzH (3,5-dimethylpyrazole), and indzH (indazole)) complexes are synthesized via chlorido abstraction from cis -[Ru(bipy) 2 Cl(az*H)]OTf. The latter are obtained from cis -[Ru(bipy) 2 Cl 2 ] after the subsequent coordination of the 1,2-azole. All the compounds are characterized by 1 H, 13 C, 15 N NMR spectroscopy as well as IR spectroscopy. Two chlorido complexes (pzH and indzH) and two aquo complexes (indzH and dmpzH) are also characterized by X-ray diffraction. Photophysical and electrochemical studies were carried out on all the complexes. The photophysical data support the phosphorescence of the complexes. The electrochemical behavior of all the complexes in an Ar atmosphere indicate that the oxidation processes assigned to Ru(II) → Ru(III) occurs at higher potentials in the aquo complexes. The reduction processes under Ar lead to several waves, indicating that the complexes undergo successive electron-transfer reductions that are centered in the bipy ligands. The first electron reduction is reversible. The electrochemical behavior in CO 2 media is consistent with CO 2 electrocatalyzed reduction, where the values of the catalytic activity [ i cat (CO 2 )/ i p (Ar)] ranged from 2.9 to 10.8. Controlled potential electrolysis of the chlorido and aquo complexes affords CO and formic acid, with the latter as the major product after 2 h. Photocatalytic experiments in MeCN with [Ru(bipy) 3 ]Cl 2 as the photosensitizer and TEOA as the electron donor, which were irradiated with >300 nm light for 24 h, led to CO and HCOOH as the main reduction products, achieving a combined turnover number (TON CO+HCOO - ) as high as 107 for 2c after 24 h of irradiation.

Cationic fac -[Re(CO) 3 (pz*H)(pypzH)]OTf (pz*H = pyrazole, pzH; 3,5-dimethylpyrazole, dmpzH; indazole, indzH; 3-(2-pyridyl)pyrazole, pypzH) were obtained from fac -[ReBr(CO) 3 (pypzH)] by halide abstraction with AgOTf and subsequent addition of the corresponding pyrazole. Successive deprotonation with Na 2 CO 3 and NaOH gave neutral fac -[Re(CO) 3 (pz*H)(pypz)] and anionic Na{ fac -[Re(CO) 3 (pz*)(pypz)]} complexes, respectively. Cationic fac -[Re(CO) 3 (pz*H)(pypzH)]OTf, neutral complexes fac -[Re(CO) 3 (pz*H)(pypz)], and fac -[Re(CO) 3 (pypz) 2 Na] were subjected to photophysical and electrochemical studies. They exhibit phosphorescent decays from a prevalently 3 MLCT excited state with quantum yields (Φ) in the range between 0.03 and 0.58 and long lifetimes (τ from 220 to 869 ns). The electrochemical behavior in Ar atmosphere of cationic and neutral complexes indicates that the oxidation processes assigned to Re I → Re II occurs at lower potentials for the neutral complex compared to cationic complex. The reduction processes occur at the ligands and do not depend on the charge of the complexes. The electrochemical behavior in CO 2 saturated media is consistent with CO 2 electrocatalyzed reduction, where the values of the catalytic activity [ i cat (CO 2 )/ i cat (Ar)] ranged from 2.7 to 11.5 (compared to 8.1 for fac -[Re(CO) 3 Cl(bipy)] studied as a reference). Controlled potential electrolysis for the pyrazole cationic ( 3a ) and neutral ( 4a ) complexes after 1 h affords CO in faraday yields of 61 and 89%, respectively. These values are higher for indazole complexes and may be related to the acidity of the coordinated pyrazole.

We report the use of a tetraborylated perylenediimide as starting material for the preparation of a tetracorannulene-perylenediimide that is able to bind up to two fullerene-C 60 molecules by host-guest molecular recognition with preference over C 70 . Titration with fullerene-C 60 is followed by a dramatic shift of the aromatic signals in 1 H NMR and an initial increase in the fluorescence of the system. By this simple mechanism, fluorogenic sensing of fullerene-C 60 is easily accomplished by an unprecedented fluorescent turn-on mechanism.

We have developed new functionalized polymers capable of being easily coated by gold nanoparticles, uniformly distributed on the surface of the polymers, by simply adding a gold(III) solution in water to the polymers. The polymer-supported gold nanoparticle material was used as an efficient portable and reusable catalyst for Suzuki reactions in mixed organic-aqueous solvents.

Enantiopure 3-carboxamide-1,4-benzodiazepin-5-ones were synthesized via the Ugi reaction followed by the Staudinger/aza-Wittig or reduction reactions in only two steps. A complete reversal of diastereoselectivity was achieved depending on the cyclization methodology employed. The different orientation of the C3 substituent in our 3-substituted 1,4-benzodiazepin-5-ones with respect to the most studied 1,4-benzodiazepin-2-ones makes them complementary in the development of new drugs because the primary source of binding selectivity of 1,4-benzodiazepines is the selective recognition of ligand conformations by the receptor.

An array of fluorogenic probes is able to discriminate between nerve agents, sarin, soman, tabun, VX and their mimics, in water or organic solvent, by qualitative fluorescence patterns and quantitative multivariate analysis, thus making the system suitable for the in-the-field detection of traces of chemical warfare agents as well as to differentiate between the real nerve agents and other related compounds.

A quinoline-indene derivative is described as a new highly selective and sensitive chromogenic and turn-on fluorogenic probe for the naked-eye detection of copper(II) cation in water-acetonitrile 1:1 mixture.

5-Oxobenzo[e][1,4]diazepine-3-carboxamides were synthesized by sequential Ugi reaction-Staudinger/aza-Wittig cyclization. The pseudopeptidic backbone of the new benzodiazepine derivatives superimposed well with type I, I', II, and II' beta-turn motifs. The intermediate Ugi adducts were characterized as two conformers of the enol form by the correlation between (1)H NMR spectra and X-ray diffraction structures of model compounds.

New ferrocene derivatives bearing two donor-acceptor systems are capable of selectively sensing cations and anions by cooperative binding of the two alpha,alpha'-groups bonded to the ferrocene nucleus, thus permitting the naked-eye selective colorimetric detection of copper[II] cation and acetate, benzoate, or cyanide anions, which are ions of toxicological and biological relevance.

[structure: see text] A new sensory MCM-41-based material for the colorimetric sensing and discrimination of amines has been developed.

[reaction: see text] Reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S(2)Cl(2) gave atropisomeric (by dynamic NMR) 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiole-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give a novel class of stable thioacid chlorides, which in turn reacted with 1 or 2 equiv of secondary amines to give thioamides.

We report the synthesis of some new polysulfur-nitrogen heterocycles by cycloaddition reactions to readily available tricyclic condensed 1,2-dithiole-3-thiones. Thus, treatment of bis[1,2]dithiolopyrrole ketothione 1 with diacyl acetylenes gave the bis-aducts 2a-d. On the other hand, cycloaddition of bis[1,2]dithiolo[1,4]thiazine ketothione 3 with 1 equiv of acyl or diacyl acetylenes gave [1,3]dithiolylidenyl[1,2]dithiolo[1,4]thiazines 4a-f in fair to high yields. Catalysis by scandium triflate was used in the reactions that implied the less reactive dipolarophiles. Treatment of 3 with 2 equiv of DBA gave the bis-aduct 5a, and reaction of 4c with DMAD gave the mixed bis-adduct 5b. Cyclic voltammetry of selected examples showed irreversible processes that were influenced by the electrochemical activity of peripheral groups bonded to the heterocyclic system.

The reaction of N -(2-chloroethyl)diisopropylamine 1a with S 2 Cl 2 allows the selective one-pot preparation of the tricyclic 4-(2-chloroethyl) bisdithiolothiazines 2 - 4 or, by addition of phosphorus pentasulfide at a late stage in the reaction, of the dithiolothiazine 5 . The chloroethyl derivative 2 is also obtained from (2-diisopropylamino)ethanethiol 1b , or its disulfide 1c , with S 2 Cl 2 , in a rare conversion of a thiol or disulfide into the corresponding chloro compound. Compounds 2 and 5 are also obtained from N -(2-hydroxyethyl)diisopropylamine 1d , though in much lower yields. The reaction of N -(2-phenylthioethyl) ( 1e ) or N -(2-phthalimidoethyl)diisopropylamines 1f , g affords bisdithiolothiazines 7 , 8 , 9 , and 11 and the dithiolopyrrole 10 . A coherent set of reaction pathways for the formation of these products is proposed. X-ray crystallography shows that the bisdithiolothiazine ring system of 2 is folded out of planarity about the thiazine N-S vector, with the N -chloroethyl group folded back over the thiazine ring with the chlorine atom lying above the thiazine sulfur atom; the dithiolothiazine ring system of 5 has the thiazine ring in a "sofa" conformation.