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A novel catalytic system of a nickel(II) complex of (E)-N′-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy-benzohydrazide (APH) supported on graphene oxide (GO) has been prepared. Detailed characterization of the synthesized catalyst has been carried out using NMR, FTIR, HRMS, PXRD, Raman, SEM, TEM, EDX and XPS. Its catalytic efficiency has been explored for the synthesis of various bis(indolyl)methane derivatives. The optimized reaction conditions prove that the catalyst is highly efficient, performs under mild conditions and is required in a very small amount (2 wt%). A diversified library of bis(indolyl)methane derivatives containing various electron donating and withdrawing substituents has been developed in high to excellent yields. The catalyst is equally efficient towards heterocyclic aldehydes. Moreover, owing to the strong covalent interaction between the APH–Ni(II) complex and GO, the catalyst shows outstanding recyclability for six subsequent cycles without any significant loss in activity. [ABSTRACT FROM AUTHOR]

A series of new organic hybrid polyoxovanadate clusters [V4O4(μ-OH)2(acac)2(Htri)2] (1, H3tri = tris(hydroxymethyl) aminomethane, acac = acetylacetone), [V4O4(acac)2(Htri)2(L)2] {HL = methanol (2), ethanol (3a and 3b), ethylene glycol (4) and benzyl alcohol (5)}, {V4O4(H2O)2(tri-acetamide)2(CH3COO)2} (6, H3tri-acetamide = N-(2-hydroxy-1,1-bis-hydroxymethyl-ethyl)-acetamide), [V6O8(μ-OH)2(Htri)3]·6H2O (7) and [V14O18(tri)2(Htri)6(HCOO)(CH3COO)]·2H2O (8) were prepared by hydro(solvo)thermal methods and characterized structurally. 1 contains [VO(OH)(acac)] and [VO2(Htri)] units, which are further interconnected via common edges to build a tetravanadyl cluster [V4O4(OH)2(acac)2(Htri)2] with the double-deficient cube [V4O6]. The tetravanadyl cluster frameworks of 2–5 can be derived from the tetravanadyl cluster of 1 by replacing two –OH groups with two deprotonated organic alcohol ligands, namely, CH3O− (2), CH3CH2O− (3a and 3b), HO(CH2)2O− (4) and C6H5CH2O− (5). Interestingly, both 3a and 3b have the same chemical structure, but they exhibit different conformational polymorphisms [denoted as α-type (3a) and β-type (3b)]. Such conformational polymorphisms within the polyoxovanadate clusters incorporating tris(hydroxymethyl)methane derivatives emerged for the first time. 6 displays another tetravanadyl cluster {V4O4(H2O)2(tri-acetamide)2(CH3COO)2} with a [V4O16] fragment, where the tri-acetamide unit comes from the amidation reaction of H3tri and acetic acid and caps the tetrahedral void of the tetravanadyl cluster. The polyoxovanadate cluster of 7 can originate from the Lindqvist-type hexavanadyl cluster [V6O19] by replacing nine μ-oxides with nine alkoxides of three tri-acetamide3− ligands. 8 exhibits a fully reduced tetradecavanadyl cluster based on the linkage of two heptavanadyl clusters via two O bridges. The magnetic properties of 1–8 show typical antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

Effective research in green chemistry requires new and applicable synthetic techniques. In this regard, for the first time, a green method is reported for the immobilization of iminodiacetic acid–Ni complex on the surface of CoFe2O4 magnetic nanoparticles. The obtained nanocomposite was characterized via chemical and physical techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), inductively coupled plasma-optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), X-ray mapping and thermal gravimetric analysis (TGA) techniques. In addition, catalytic activity of the as-prepared nanocomposite was examined in the synthesis of polyhydroquinoline and bis(pyrazolyl)methane derivatives in green conditions. It was observed that all the products were obtained during short reaction time and in good to excellent yields. Importantly, the catalyst was easily recovered and recycled by magnetic field for five successive times without noticeable decrease in its catalytic activity. [ABSTRACT FROM AUTHOR]

Production of biodiesel from biomass resources usually requires elongation of carbon numbers from typical C5 and C6 platform molecules through C–C coupling reactions, which were catalyzed by acid, base or metal catalysts traditionally. Herein, a catalyst-free method was developed to produce bis(furan-2-yl)methane derivatives (BFMs) from furfuryl alcohol derivatives (FAs) in the presence of H2O and air without any other additional catalysts. An 81% yield of bis(5-methylfuran-2-yl)methane (BMFM) can be obtained from 5-methylfurfuryl alcohol (5-MFA) and a 59% total yield of C11 biodiesel was obtained from 5-methylfurfural (5-MF). In addition, a H2O and air mediated free radical decarboxylation mechanism was proposed based on the detailed mechanistic studies. This strategy offers a green, low-cost and environmentally friendly approach to synthesize biodiesel precursors from biomass based platform molecules. [ABSTRACT FROM AUTHOR]

The compounds EtOC(=O)CHNNPR3 (R = Ph 1, Cy 2, tBu 3) were prepared via the reactions of the diazomethane and a phosphine. In subsequent reactions with B(C6F5)3, the compounds 2 and 3 are shown to exhibit Lewis basicity at the carbonyl oxygen affording EtOC(=O(B(C6F5)3))CHNNPR3 (R = Cy 5, tBu 6). Reactions of 5 and 6 with water or phenol illustrated the Brønsted basicity at the nitrogen atom adjacent phosphorus, affording the compounds, [EtOC(=O)CHNNHPR3][HOB(C6F5)3] (R = Cy 7, tBu 8) and [EtOC(=O)CHNNHPR3][PhOB(C6F5)3] (R = Cy 9, tBu 10), respectively. The formulation of these products is confirmed via spectroscopic and crystallographic studies, and insight is garnered from computations. [ABSTRACT FROM AUTHOR]

A catalytic system consisting of 5 mol% CoCl2 and 10 mol% isoquinoline allows a convenient cross-coupling of benzylic zinc reagents with various aryl and heteroaryl bromides or chlorides leading to polyfunctionalized diaryl- and aryl-heteroaryl-methane derivatives. [ABSTRACT FROM AUTHOR]

An efficient self-assembled methanoproline–thiourea organocatalyst for the synthesis of optically active 6-isopropyl-3,4-dihydro-pyrimidines via an asymmetric Biginelli reaction was developed, which is superior to the individual precatalyst. A wide range of optically active 6-isopropyl-3,4-dihydropyrimidines with remarkable pharmacological interest was obtained in high yields with excellent enantioselectivities (up to 99% ee). A plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction. [ABSTRACT FROM AUTHOR]

Using a purification method introduced earlier based on redox properties it was possible to isolate Sc3N@Ih-C80 and Sc3N@D3h-C78 and a mixture of Sc3N@D5h-C80 and Sc3N@D3-C68. Taking advantage of their chemical reactivity differences, Sc3N@D5h-C80 was isolated from Sc3N@D3-C68 followed by further functionalization, giving rise to five new methano-derivatives of Sc3N@D5h-C80. [ABSTRACT FROM AUTHOR]

A new sensor 2,2′-((1E,1′E)-((3,3′-dimethyl-[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene))bis(methanylylidene))diphenol (YT) based on the combination of phenolic hydroxy and imine groups was used as an efficient colorimetric and “turn on” fluorescent sensor for fluoride anions. The receptor exhibits high selectivity and sensitivity for sensing F−. Furthermore, the enhanced fluorescence caused by fluoride could be reset upon the addition of calcium ions to the complex solution. The fluorescence changes of YT upon the addition of F− and Ca2+ were utilized as an INHIBIT logic gate at the molecular level, using F− and Ca2+ as chemical inputs and the fluorescence intensity signal as the output. [ABSTRACT FROM AUTHOR]

Photo-crosslinking agents have emerged as critical tools to investigate protein–protein interactions in complex proteomes, but there are few photocrosslinkers available at the moment. Here, we report the first rational design of a photo-crosslinking BODIPY fluorophore (pcBD) and its biological application for biomolecule labeling. As a photosensitizing functional motif, an aryl ketone group was incorporated into the BODIPY fluorophore, and a series of proteins were labeled by pcBD compounds upon UV irradiation. In order to investigate protein–protein interactions in a protein mixture, amino-functionalized pcBD was prepared and covalently attached to a ubiquitin ligase binding peptide. Upon UV irradiation, we could successfully visualize the substrates in the total lysate. These results provided a proof of concept for spatially controllable tagging via photo-activation of the pcBD scaffold, and demonstrated its potential usage for in situ labeling applications. [ABSTRACT FROM AUTHOR]

A facile one-pot impregnation–thermal reduction strategy was employed to fabricate sandwich-like graphene–g-C3N4 (GCN) nano-composites using urea and graphene oxide as precursors. The GCN sample exhibited a slight red shift of the absorption band edge attributed to the formation of a C–O–C bond as a covalent cross linker between graphene and g-C3N4. The GCN sample demonstrated high visible-light photoactivity towards CO2 reduction under ambient conditions, exhibiting a 2.3-fold enhancement over pure g-C3N4. This was ascribed to the inhibition of electron–hole pair recombination by graphene, which increased the charge transfer. [ABSTRACT FROM AUTHOR]

A new PC(sp³)P ligand N,N'-bis(diphenylphosphino)dipyrromethane [PCH2P] (1) was prepared and its iron, cobalt and nickel chemistry was explored. Two pincer-type complexes [PCHP]Fe(H)-(PMe3)2 (2) and [PCHP]Co(PMe3)2 (4) were synthesized in the reaction of 1 with Fe(PMe3)4 and Co(Me)(PMe3)4. 1 reacted with Co- (PMe3)4 and Ni(PMe3)4 to afford Co(0) and Ni(0) complexes [PCH2P]Co(PMe3)2 (3) and [PCH2P]Ni(PMe3)2 (5). The structures of complexes 2-5 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

The tautomeric properties of di(2-pyridyl)methane and its benzoannulated derivatives were studied using a computational approach (M05/6-31G(2d,p)). Our analysis showed that the degree of cyclic π-electron delocalization in benzene and pyridine rings is directly connected to the effect of resonance present in quasi-rings formed by intramolecular hydrogen bonds of the N–H…N type. This direct relation can be explained using two concepts, namely, the concept of Clar's aromatic sextet and the Leffler–Hammond concept originally developed for the explanation of the energy relation between ground-state and transition-state structures corresponding to proton transfer in H-bridges. Application of these two different concepts allows us to explain in detail the role of intramolecular hydrogen bonding in polycyclic aromatic hydrocarbons containing N heteroatoms. [ABSTRACT FROM AUTHOR]