EPR spin-trapping evidence for the direct,one-electron reduction of tert-butylhydroperoxide to the tert-butoxyl radical by copper(II): paradigm for a previously overlooked reaction in the initiation of lipid peroxidation

Lipid peroxidation is often initiated using Cu(II) ions. It is widely assumed that Cu(II) oxidizes preformed lipid hydroperoxides to peroxyl radicals, which propagate oxidation of the parent fatty acid via hydrogen atom abstraction. However, the oxidation of alkyl hydroperoxides by Cu(II) is thermodynamically unfavorable. An alternative means by which Cu(II) ions could initiate lipid peroxidation is by their one-electron reduction of lipid hydroperoxides to alkoxyl radicals, which would be accompanied by the generation of Cu(III). We have investigated by EPR spectroscopy, in conjunction with the spin trap 5,5-dimethyl-1-pyrroline N-oxide, the reactions of various Cu(II) chelates with tert-butylhydroperoxide. Spectra contained signals from the tert-butoxyl, methyl, and methoxyl radical adducts. In many previous studies, the signal from the methoxyl adduct has been assigned incorrectly to the tert-butylperoxyl adduct, which is now known to be unstable, releasing the tert-butoxyl radical upon decomposition. This either is trapped by 5,5-dimethyl-1-pyrroline N-oxide or undergoes beta-scission to the methyl radical, which either is trapped or reacts with molecular oxygen to give, ultimately, the methoxyl radical adduct. By using metal chelates that are known to be specific in either their oxidation or reduction of tert-butylhydroperoxide (the Cu(II) complex of bathocuproine disulfonic acid and the Fe(II) complex of diethylenetriaminepentaacetic acid, respectively) for comparison, we have been able to deduce, from the relative concentrations of the three radical adducts, that the Cu(II) complexes tested each reduce tert-butylhydroperoxide directly to the tert-butoxyl radical. These findings suggest that a previously overlooked reaction, namely the direct reduction of preformed lipid hydroperoxides to alkoxyl radicals by Cu(II), may be responsible for the initiation of lipid peroxidation by Cu(II) ions.     

Low coordinate germanium and tin compounds (ArO)2ME and (ArO)2MM′Ln M=Ge, Sn; E=S, Se, –NSiMe3 M′=Cr, W, Fe, Pt [Ar=2,4,6-tris((dimethylamino)methyl)phenyl-]

The reactions of the divalent species (ArO)₂M (Ar=2,4,6-[(CH₃)₂NCH₂]₃C₆H₂; M=Ge, Sn) with either Me₃SiN₃, elemental S₈, Se or transition metal complexes M′(CO)_n+1 (M′=Fe, n=4; M′=Cr, W; n=5) (Ph₃P)₂Pt·C₂H₄ have resulted in the isolation of either the new stable formal metallanimines (ArO)₂M=N–SiMe₃, germanethione, -selone (ArO)₂Ge=E (E=S, Se) (the expected formations of the stannanethione and -selone were not observed), or the (ArO)₂M=M′(CO)_n, (ArO)₂M=Pt(PPh₃)₂ complexes, respectively. The direct oxidation of the (ArO)₂M species with various oxidizing agents led to the formation of the corresponding metalloxanes [(ArO)₂M–O–]₂. All of the chalcogenido- and transition metal–metal 14 complexes have been physicochemically and chemically characterized. The reactions of the (ArO)₂Ge=E (E=S, Se) compounds with 3,5-di-tert-butyl-1,2-benzoquinone produced, by extrusion of sulfur or selenium, the dioxametalloles corresponding to the formal addition of the divalent species (ArO)₂M to the benzoquinone. A substitution reaction of chalcogen (S/Se) has been observed permitting to go from germaneselone to germanethione.     

Synthesis, Characterization, and Bonding of Two New Heteropolychalcogenides: alpha-CsCu(S(x)()Se(4-x)) and CsCu(S(x)()Se(6-x))

The Cs-Cu-Q (Q = S, Se) system has been investigated using copper metal, cesium chloride, and alkali-metal polychalcogenide salts under mild hydrothermal reaction conditions. Heteropolychalcogenide salts and mixtures of known polysulfide and polyselenide salts have been used as reagents. The reaction products contain the alpha-CsCuQ(4) and CsCuQ(6) structures. The alpha-CsCuQ(4) phase exhibits a smooth transition in lattice parameters from the pure sulfur to the pure selenium phases, based on Vegard's law. The CsCuQ(6) phase has been prepared as the pure sulfur analog and a selenium rich analog. The single-crystal structures of the disordered compounds alpha-CsCuS(2)Se(2) (P2(1)2(1)2(1), Z = 4, a = 5.439(1) ?, b = 8.878(2) ?, c = 13.762(4) ?) and CsCuS(1.6)Se(4.4) (P&onemacr;, Z = 2, a = 11.253(4) ?, b = 11.585(2) ?, c = 7.211(2) ?, alpha = 92.93 degrees, beta = 100.94 degrees, gamma = 74.51 degrees ) have been solved using a correlated-site occupancy model. These disordered structures display a polychalcogenide geometry in which the sulfur atoms prefer positions that are bound to copper. The optical absorption spectra of these materials have been investigated. The optical band gap varies as a function of the sulfur-selenium ratio. Extended Hückel crystal orbital calculations have been performed to investigate the electronic structure and bonding in these compounds in an attempt to explain the site distribution of sulfur and selenium.     

有机硒和碲化学的新进展

本文着重对最近几年来有机硒和碲化合物在有机合成中的应用进行了简要的综述。现在就硒和碲化合物作为反应试剂、在有机分子中引入硒和碲的方法以及从有机分中除去硒和碲的方法三个方面进行了讨论。由此也可见,有机硒和缔化合物在有机合成中的重要性。     

3-取代卓酚酮5位偶联产物的溴氧化成环反应

报道了采用溴氧化3-异丙烯基卓酚酮和3-肉桂酰基卓酚酮合成杂环并卓酮化合物的新方法。3-异丙烯基卓酚酮5位偶联产物1a-1f和3-肉桂酰基卓酚酮5位偶联产物3a-3d分别在吡啶介质中与过量溴作用生成5-取代苯偶氮基-7-溴-3-甲基-8-氢环庚并呋喃-8-酮2a-2f和6-取代苯偶氮基-2-苯基-8-溴-4,9-二氢环庚并吡喃-4,9-二酮4a-4d。     

A Simple and Convenient Strategy for the Synthesis of Novel Ten,Twelve, and Fourteen‐membered Phosphorus Macrocyclic Compounds

Synthesis of the title compounds 4(a – i) was accomplished through a two‐step process. The synthetic route involves the cyclization of equimolar quantities of 2,2′‐methylene(methyl)bis(4,6‐di‐tert‐butyl‐phenol) ( 1 ) with tris‐(2‐chloro‐ethyl) phosphite ( 2a ), tris‐(2‐bromo‐ethyl) phosphine ( 2b ), and tris‐bromo methyl phosphine ( 2c ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C. They were further converted to the corresponding oxides, sulfides, and selenides under N₂ atmosphere by reacting them with hydrogen peroxide, sulfur, and selenium, respectively ( 4a – c , 4d – f, and 4g – i ). But the compounds 6a , b were prepared by the direct cyclocondensation of equimolar quantities of 1 with (2‐chloro‐ethyl)‐phosphonic acid dibromomethyl ester ( 5a ) and (2‐chloro‐ethyl)‐phosphonic acid bis(2‐bromo‐ethyl) ester ( 5b ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C in moderate yields. All the newly synthesized compounds 4 ( a – i ) and 6 ( a – b ) exhibited moderate in vitro antibacterial and antifungal activities.     

Antioxidant activity of eugenol and related monomeric and dimeric compounds

Since the inhibitory effect of eugenol (a), which was isolated as an antioxidative component from plant, Caryopylli flos, on lipid peroxidation was less than that of alpha-tocopherol, we synthesized the eugenol-related compounds dieugenol (b), tetrahydrodieugenol (c), and dihydroeugenol (d), to find new strong antioxidants and assessed them for their inhibitory effect on lipid peroxidation and scavenging ability for superoxide and hydroxyl radicals. The antioxidative activities were in the order: (b)>(c)>(d)>(a) for the thiobarbituric acid reactive substance (TBARS) formation. These results suggest that the dimerized compounds have higher antioxidant activities than that of the monomers. Electron spin resonance (ESR) spin trapping experiments revealed that eugenol and its dimer, having allyl groups in the structure, scavenged superoxide, and that only eugenol trapped hydroxyl radicals under the conditions used. These finding suggest that eugenol and dieugenol have a different mechanism of antioxidation, i.e. eugenol may inhibit lipid peroxidation at the level of initiation, however, the related dimeric compounds may inhibit lipid peroxidation at the level of propagation of free radical chain reaction like alpha-tocopherol.     

Chemistry of benzo[b]furan. V.. Synthesis of substituted thia-analogs and oxa-analogs of dihydrorutecarpine and evodiamine

Cycloaddition of 3,4-dihydrobenzo[b]thieno[2,3-c]pyridine ( 6 ) with the sulfinamide anhydride 9 (R = H) afforded the thia-analog of dihydrorutecarpine ( 2a ). Condensation of the imine 6 with the sulfinamide anhydride 9 (R = CH₃) gave the thia-analog of evodiamine ( 2b ). Starting from 1-methyl-3,4-dihydrobenzo[b]thieno[2,3-c]pyridine ( 12 ) and 1-methyl-3,4-dihydrobenzo[b]furo[2,3-c]pyridine ( 14 ), a series of 3-methyl derivatives of thia-analogs of dihydrorutecarpine and evodiamine ( 2c-2i ) and oxa-analogs of dihydrorutecarpine and evodiamine ( 1a-1g ) were similarly prepared.     

Spiropentane mimics of nucleosides: analogues of 2'-deoxyadenosine and 2'-deoxyguanosine. Synthesis of all stereoisomers, isomeric assignment, and biological activity

Synthesis of spirocyclic analogues of 2'-deoxyadenosine and 2'-deoxyguanosine (12a-15a and 12b-15b) is described. Rhodium-catalyzed reaction of ethyl diazoacetate with methylenecyclopropane 19, obtained from 2-bromo-2-bromomethylcyclopropane 17 via debromination (16), reduction (18), and acetylation (19), gave a mixture of all four isomeric spiropentanes 20a-20d. Hydrolysis afforded hydroxy carboxylic acids 21a-21d. Acetylation of separated proximal + medial-syn isomers 21a + 21b and medial anti + distal isomers 21c + 21d furnished acetates 22a + 22b and 22c + 22d. Curtius rearrangement effected by diphenylphosphoryl azide in tert-butyl alcohol performed separately with mixtures 22a + 22b and 22c + 22d led to BOC-amino spiropentanes 23a + 23b and 23c + 23d. After deacetylation all isomers 24a-24d were separated and deprotected to give aminospiropentane hydrochlorides 25a-25d. Free bases were of limited stability. The heterocyclic moieties were introduced into individual isomers 25a-25d via 6-chloropurine derivatives 26a-26d or 30a-30d. Ammonolysis of 26a-26d furnished the adenine isomeric series 12a-15a, whereas guanine derivatives 12b-15b were obtained by hydrolysis of 30a-30d with formic acid. The isomeric assignments followed from IR spectra of BOC-aminospiropentanes 24a-24d and NMR spectra of 12a-15a including NOE and (H,H) COSY. The proximal and medial-syn isomers 12a and 12b were modest inhibitors of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in culture, whereas the medial-anti isomer 12c was a substrate for adenosine deaminase. The distal isomer 15b was an anti-EBV agent. The medial-syn phosphoralaninate 34 was an effective inhibitor of HCMV replication in vitro. It was also active against herpes simplex virus type 1 (HSV-1), varicella zoster virus (VZV), human immunodeficiency virus (HIV-1), hepatitis B virus (HBV), and EBV with a varying degree of cytotoxicity.     

Facile one-pot synthesis of functionalized organophosphonate esters via ketone insertion into bulky arylphosphites

The reaction of phosphorus trichloride with 2,6-diisopropyl phenol in the presence of LiCl under reflux conditions for 24 h produces a mixture of (ArO)PCl₂ and (ArO)₂PCl (Ar = 2,6-iPr₂C₆H₃). The hydrolysis of the aryloxy compounds in acetone/H₂O results in the formation of two novel phosphonate ester derivatives [(ArO)P(O)(OH)(CMe₂OH)] (1) and [(ArO)₂P(O)(CMe₂OH)] (2), respectively in a moderate yield. The title compounds have presumably formed via acetone insertion to the P-H bonds of (ArO)P(O)(H)(OH) and (ArO)₂P(O)(H), respectively, in the presence of HCl produced during the hydrolysis. Compounds 1 and 2 have been characterized by elemental analysis, and ESI-mass, Infrared and NMR spectroscopic techniques. Further, solid state structures of 1 and 2 have been established by single crystals X-ray diffraction studies.     

Furopyridines. IX. Syntheses and properties of 3-ethoxy derivatives of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

Reaction of ethyl 3-ethoxycarbonylmethoxyfuropyridine-2-carboxylates 2a-2d with sodium ethoxide afforded 3-ethoxy derivatives 3a-3d which converted to 3-ethoxyfuropyridines 5a-5d by hydrolysis and decarboxylation of the ester group. Vilsmeier reaction of 5a and 5b gave 2-formyl-3-ethoxy derivatives 6a and 6b and 2-formyl-3-chloro derivatives 7a and 7b , while 5c and 5d did not give any formyl compound. Bromination of 3-ethoxyfuropyridines with 1 equivalent mole of bromine gave 2-bromo-3-ethoxyfuropyridines 9a-9d , whereas reaction with 3 equivalents of bromine yielded 2,2-dibromo-3,3-diethoxy-2,3-dihydrofuropyridines ( 10a and 10b ) and/or 2-bromo-3,3-diethoxy-2,3-dihydrofuropyridines 11b , 11c and 11d . Treatment of compounds 5a-5d with n-butyllithium in hexane-tetrahydrofuran at ?70° and subsequent addition of N,N-dimethylformamide yielded 2-formyl derivatives 6a-6d .     

Organotellurium(IV) complexes of N-methylisatin-o-aminothiophenol Schiff base: Preparation,characterization, DFT,molecular docking studies,antimicrobial and antioxidant activity

The reactions of organotellurium(IV) chlorides (RTeCl₃ and R₂TeCl₂) with Schiff base(NMeIATP) derived by condensation of N-methylisatin with 2-aminothiophenol results in the formation of new organotellurium(IV) complexes (4a-4f) of type RTeCl₂.NMeIATP and R₂TeCl.NMeIATP (where R = 4-Methoxyaryl, 4-Hydroxyaryl and 3-Methy-4-hydroxyaryl; aryl = phenyl). These complexes were characterized by different experimental and spectroscopic techniques like elemental analyses, molar conductance, SEM analysis, FT-IR, DFT calculations, powder X-ray diffraction, mass spectrometry, ¹H NMR, ¹³C NMR, UV–Vis and Thermogravimetric analysis. These spectroscopic studies revealed that ligand acted as monobasic tridentate ligand coordinated with tellurium metal through Carbonyl oxygen, azomethine nitrogen and sulphur atom from the 2-aminothiophenol ring. The molecular geometries of NMeIATP and its organotellurium(IV) complexes(4a-4f) were optimized and quantum mechanical parameters were calculated by using DFT/B3LYP basis sets in Guassian09 program. Based on the spectral results, suitable geometries of the complexes are purposed. Molecular docking studies were carried out to determine the binding energy between NMeIATP and complexes with receptor proteins: S. aureus (3ty7), B. subtilis (5h67) and E. coli (3t88). Antioxidant activity of NMeIATP and organotellurium(IV) complexes were evaluated by DPPH assay. The radical scavenging activity(IC₅₀ value) of complex 4a (IC₅₀ = 59.08 μg/ml) was found to be greater than other compounds. NMeIATP and organotellurium(IV) complexes were tested against different bacteria and fungi. MIC values show that complexes possess better antimicrobial activity than Schiff base (NMeIATP).     

Synthesis and bioactivity evaluation of eugenol hybrids obtained by Mannich and 1,3 dipolar cycloaddition reactions

Design, synthesis, and bioactivity evaluation of novel mannich bases ( 2a-2j ) and triazole-chalcone derivatives ( 7a-7k ) of Eugenol 1 were reported. Among all the derivatives tested for antiproliferative activity, di-amine manich derivative 2b (32.92 μM), and 4-methoxy chalcone triazole derivative 7d (33.05 μM) significantly inhibited HepG2 cell lines when compared to the standard doxorubicin (37.29 μM). Whereas most of the compounds such as diethylamine 2a (17.75 μM), (aminomethyl) methane diamine 2b (17.02 μM), and bis (chloromethyl) amine 2c (20.12 μM) showed moderate to better inhibition towards MCF-7 cell lines. The synthesized analogues were also tested for antidiabetic and antiobesity potentials. Compounds 2f (55.50%), 2c (54.34%), 7g (55.5%), and 2a (55.5%) have shown moderate inhibitory potentials toward intestinal α-glucosidase enzyme when compared to the standard Acarbose (72.86%). Likewise, compounds 7d (82.95%), 7f (76.19%), 7g (74.81%), 7e (74.81%), and 2g (72.50%) have shown significant to moderate inhibitory potentials toward Pancreatic lipase enzyme when compared to the standard orlistat (91.10%). ROS induces life-threatening diseases like diabetes, cancer, etc., and antioxidants play a major role in controlling their production. Compounds 2c (99.81%), 2i (99.80%), 2d (99.26%), 2g (98.79%), and 2f (98.42%) have shown significant antioxidant profiles in ABTS assay when compared to the standard Trolox (99.07%). Further, In silico Molecular docking and pharmacokinetic screening of the eugenol derivatives complemented the in vitro results indicating the drug likeness of the obtained active compounds.     

Isostructural potassium and thallium salts of sterically crowded triazenes: a structural and computational study

Because of their similar cationic radii, potassium and thallium(I) compounds are usually regarded as closely related. Homologous molecular species containing either K(+) or Tl(+) are very rare, however. We have synthesized potassium and thallium salts MN3RR' derived from the biphenyl- or terphenyl-substituted triazenes Tph2N3H (1a), Dmp(Mph)N3H (1b), Dmp(Tph)N3H (1c), and (Me4Ter)2N3H (1d) (Dmp=2,6-Mes 2C6H3 with Mes=2,4,6-Me3C6H2; Me4Ter=2,6-(3,5-Me2C6H3)2C6H3; Mph=2-MesC6H4; Tph=2-TripC6H4 with Trip=2,4,6-(i)Pr3C6H2). The potassium complexes 2a- d were obtained in almost quantitative yield from the reaction of 1a- d with potassium metal in n-heptane. Metalation of 1a- d with TlOEt afforded the thallium triazenides 3a- d in high yields. All new compounds have been characterized by (1)H and (13)C NMR spectroscopy, elemental analysis, and X-ray crystallography and for selected species by melting point (not 3b), IR spectroscopy (2a, 2d, 3a, 3c, 3d), and mass spectrometry (2a, 3c). In the solid-state structures of monomeric 2a and 3a, quasi-monomeric 2b, 3b, 2c, and 3c, and dimeric 2d and 3d additional metal-eta (n)-pi-arene-interactions to the flanking arms of the biphenyl- and terphenyl groups in the triazenide ligands of decreasing hapticity n are observed. Remarkably, all homologous potassium and thallium complexes crystallize in isomorphous cells. For 2a and 3a, the nature of the M-N and M...C(arene) bonding was studied by density functional theory calculations.     

Synthesis of symmetrical 1,5-bis-thio-substituted anthraquinones for cytotoxicity in cultured tumor cells and lipid peroxidation

The synthesis of a series of anthraquinone moieties bearing symmetrical sulfur-linked substituents in the 1 and 5 positions is described. These compounds were evaluated for their ability to inhibit the growth of suspended rat glioma C6 cells and human hepatoma G2 cells, respectively. In addition, the redox property of the compounds was determined based on the inhibition of lipid peroxidation in model membranes. Compounds 2a and 2h in this series compared favorably and exhibited the most potent cytotoxicity (0.02, 0.05 microM) against C6 cells in the XTT colorimetric assay. As far as redox properties are concerned, all bis-thio-anthraquinones show potential lipid peroxidation in model membranes very close to that of mitoxantrone (MX), and 2a, 2d, 2e, 2i, 2j, and 2k have more potential than that of MX. The lack of cytotoxicity of compound 2i cannot be related to lipid peroxidation, but the steric and electronic properties of the side-chain substituent maybe impair effective recognition of the cleavable complex. In contrast to MX, 2a and 2h are cytotoxic in rat glioma C6 cells and do not enhance lipid peroxidation in model membranes.     

N‐Heterocyclic Carbene (NHC)‐Stabilized Silanechalcogenones: NHC→Si(R2)E (E=O,S, Se,Te)

A series of N‐heterocyclic carbene‐stabilized silanechalcogenones 2 a , b (Si?O), 3 a , b (Si?S), 4 a , b (Si?Se), and 5 a , b (Si?Te) are described. The silanone complexes 2 a , b were prepared by facile oxygenation of the carbene–silylene adducts 1 a , b with N₂O, whereas their heavier congeners were synthesized by gentle chalcogenation of 1 a , b with equimolar amounts of elemental sulfur, selenium, and tellurium, respectively. These novel compounds have been isolated in a crystalline form in high yields and have been fully characterized by a variety of techniques including IR spectroscopy, ESIMS, and multinuclear NMR spectroscopy. The structures of 2 b , 3 a , 4 a , 4 b , and 5 b have been confirmed by single‐crystal X‐ray crystallography. Due to the NHC→Si donor–acceptor electronic interaction, the Si?E (E=O, S, Se, Te) moieties within these compounds are well stabilized and thus the compounds possess several ylide‐like resonance structures. Nevertheless, these species also exhibit considerable Si?E double‐bond character, presumably through a nonclassical Si?E π‐bonding interaction between the chalcogen lone‐pair electrons and two antibonding Si? N σ* orbitals, as evidenced by their high stretching vibration modes and the shortening of the Si–E distances (between 5.4 and 6.3 %) compared with the corresponding Si? E single‐bond lengths.     

Thermal stability of selenium, sulfur and nitrogen analogous phthalazine derivatives

Differential scanning calorimetry (DSC) and thermogravimetry (TG) are analytical and quantitative methods capable of providing reliable, fast and reproducible results. These data allow establishing the thermal stability, purity degree and the polymorphic behavior of organic compounds. Thermal analysis of fusion and degradation processes was carried out on organonitrogen, organosulfur and organoselenium phthalazine derivatives to establish thermal stability criteria. Decomposition and fusion temperatures of 27 biological active compounds, synthesized by our research group were determined using TG and DSC. Analysis of the thermal data indicated that: (a) in general, nitrogen compounds are more stable than sulfur and selenium compounds; (b) thioderivatives possess degradation temperatures higher than selenium compounds; (c) the presence of selenium atoms in molecular structure has associated a minor thermal stability; (d) sulfide derivatives decomposition process have higher T_onset values than disulfide compounds; (e) there are differences in the stability due to groups selenol, methylseleno, and cyanoseleno; (f) the nature of the substituent located on the benzyl ring has no effects on selenophthalazines thermal stability.     

Strong intra- and intermolecular aurophilic interactions in a new series of brilliantly luminescent dinuclear cationic and neutral au(I) benzimidazolethiolate complexes

The structural and photophysical properties of a new series of cationic and neutral Au(I) dinuclear compounds (1 and 2, respectively) bridged by bis(diphenylphosphino)methane (dppm) and substituted benzimidazolethiolate (X-BIT) ligands, where X = H (a), Me (b), OMe (c), and Cl (d), have been studied. Monocationic complexes, [A(u2)(micro-X-BIT)(micro-dppm)](CF(3)CO(2)), were prepared by the reaction of [A(u2)(micro-dppm)](CF(3)CO(2))(2) with 1 equiv of X-BIT in excellent yields. The cations 1a-1d possess similar molecular structures, each with a linear coordination geometry around the Au(I) nuclei, as well as relatively short intramolecular Au(I)...Au(I) separations ranging between 2.88907(6) A for 1d and 2.90607(16) A for 1a indicative of strong aurophilic interactions. The cations are violet luminescent in CH(2)Cl(2) solution with a lambda(em)(max) of ca. 365 nm, assigned as ligand-based or metal-centered (MC) transitions. Three of the cationic complexes, 1a, 1b, and 1d, exhibit unusual luminescence tribochromism in the solid-state, in which the photoemission is shifted significantly to higher energy upon gentle grinding of microcrystalline samples with DeltaE = 1130 cm(-1) for 1a, 670 cm(-1) (1b), and 870 cm(-1) (1d). The neutral dinuclear complexes, [A(u2)(micro-X-BIT)(micro-dppm)] (2a-2d) were formed in good yields by the treatment of a CH(2)Cl(2) solution of cationic compounds (1) with NEt(3). 2a-2d aggregate to form dimers having substantial intra- and intermolecular aurophilic interactions with unsupported Au(I)...Au(I) intermolecular distances in the range of 2.8793(4)-2.9822(8) A, compared with intramolecular bridge-supported separations of 2.8597(3)-2.9162(3) A. 2a-2d exhibit brilliant luminescence in the solid-state and in DMSO solution with red-shifted lambda(em)(max) energies in the range of 485-545 nm that are dependent on X-BIT and assigned as ligand-to-metal-metal charge transfer (LMMCT) states based in part on the extended Au...Au...Au...Au interactions.     

Synthesis and bioactivity of 6‐bromo‐2‐(substituted)‐3‐(1‐phenyl‐ethyl)‐ 3,4‐dihydro‐1H‐ isophosphinoline 2‐chalcogenides

Synthesis of 6‐bromo‐2‐(substituted)‐3‐(1‐phenyl‐ethyl)‐3,4‐dihydro‐1H‐isophosphinoline 2‐chalco‐genides derivatives (6) were synthesized from 2‐[(1‐phenylethylamino)methyl]‐4‐bromophenol ( 1 ) by reaction with aryl/alkyl phosphoro dichloridates ( 2 ) in the presence of triethylamine at 55°C to 60°C to obtained the title compounds ( 6a‐g ). The title compounds ( 6h‐j ), were prepared via intermediate route. Few other title compounds ( 8a‐c ) were accomplished through a two step synthetic route involving 1 with dichlorophenyl phosphine ( 2a ) and dichloroethyl phosphine ( 2a,b ) in the presence of triethylamine in dry toluene under N₂ atmosphere to form the corresponding trivalent phosphorus intermediate (7) . In the second step they were further converted to the corresponding chalcogenides 8a‐c by reaction with hydrogen peroxide, sulfur and selenium respectively. They exhibited significant antibacterial, fungal and insecticidal activity.     

Synthesis of 1,2,4-triazol-5-ylidenes and their interaction with acetonitrile and chalcogens

Two new, more convenient methods for the synthesis of 1,2,4-triazol-5-ylidenes are described. Four new 1,2,4-triazol-5-ylidenes have been prepared using these methods: 1-(1-adamantyl)-3,4-diphenyl-1,2,4-triazol-5-ylidene (2a), 1-(1-adamantyl)-3-phenyl-4-(p-bromophenyl)-1,2,4-triazol-5-ylidene (2b), 1-(1-adamantyl)-3-phenyl-4-(alpha-naphthyl)-1,2,4-triazol-5-ylidene (2c), and 1-(1-adamantyl)-3,4-di(p-bromophenyl)-1,2,4-triazol-5-ylidene (2d). The X-ray crystal structures of 2d and the precursor salt 1-(1-adamantyl)-3,4-di(p-bromophenyl)-1,2,4-triazolium bromide (1e) are described. Compound 2a reacts with CH(3)CN via C-H insertion to form 1-(1-adamantyl)-3,4-diphenyl-5-cyanomethyl-5H-1,2,4-triazoline (3), and 2a and 2d react with elemental sulfur and elemental selenium, respectively, to form the corresponding thione (4) and selenone (5).