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Copper (Cu) based nanoparticles mediated organic transformations have been focused worldwide because these methodologies afford industrially important fine chemicals under mild conditions. Moreover, Cu is environment friendly and relatively inexpensive. This review highlights the important developments of Cu based nanocatalysts for organic transformations.

The novel title catalyst is successfully employed to the selective oxidation of primary and secondary alcohols with periodic acid.

The asymmetric unit of the title compound, C16H22N2O2S, contains two crystallographically independent molecules (AandB). In moleculeA, the cyclohexane ring is disordered over two orientations [occupancy ratio 0.841 (10):0.159 (10)]. In each molecule, the central carbonyl thiourea unit is nearly planar (r.m.s. deviations for all non-H atoms of 0.034 Å in moleculeAand 0.094 Å in moleculeB). In both molecules, the cyclohexane ring adopts a chair conformation. The mean plane of the cyclohexane ring makes dihedral angles of 35.8 (4) (moleculeA) and 20.7 (3)° (moleculeB) with that of the benzene ring. Each molecule features an intramolecular N—H...O hydrogen bond, which closes anS(6) ring motif. In the crystal, molecules are linkedviapairs of weak N—H...S interactions, forming inversion dimers with anR22(8) ring motif for both molecules. The crystal structure also features weak C—H...π ring interactions.

The title compound, C22H18N4OS, crystallized with four independent molecules (A,B,CandD) in the asymmetric unit. All four molecules have aZconformation about the C=N bond with the benzyl ring being inclined to the indoline ring mean planes by 73.4 (2), 77.9 (2), 73.2 (2) and 77.2 (2)° in moleculesA,B,CandD, respectively. In moleculesAandB, the phenyl ring is inclined to the mean plane of the indoline ring mean plane by 12.0 (2) and 12.2 (2)°, respectively. However, in moleculesCandD, the same dihedral angles are larger,viz.37.3 (2) and 36.4 (2)°, respectively. Consequently, the benzyl and phenyl rings are almost normal to one another in moleculesAandB[dihedral angles = 80.3 (3) and 87.1 (3)°, respectively], while in moleculesCandD, the same dihedral angles are only 48.8 (2) and 43.8 (3)°, respectively. There is an intramolecular N—H...O hydrogen bond in each molecule with anS(6) ring motif. There are also short intramolecular N—H...N and C—H...S contacts in each molecule. In the crystal, molecules are linkedviaC—H...S hydrogen bonds and C—H...π interactions, forming a three-dimensional structure. The crystal was refined as a non-merohedral twin with a final BASF value of 0.110 (1).

The title compound, C26H42N4O2S2, adopts a shallow U-shape as both pendant arms of the 1,3-substituted benzene ring are orientated in the same direction. The thione S atoms lie to the same side of the benzene ring and the carbonyl O atoms to the other. The most prominent feature of the crystal packing is the formation of inversion dimers mediated by N—H...S hydrogen bonds. One of the 2-methylpropyl groups is statistically disordered over two positions.

In the title compound, C17H25N3O2S, the terminal and central amide groups are, respectively, twisted and coplanar with the attached benzene ring [O—C—C—C torsion angles = 22.7 (3) and 5.4 (3)°]. In the central part of the molecule, the amide and thioamide residues are approximately perpendicular [C—N—C—S torsion angle = −104.98 (18)°]. Supramolecular layers with a zigzag topology are formed in the crystal packing by N—H...O, N—H...S and C—H...O interactions; these stack along c, being separated by hydrophobic interactions.

Two independent molecules with quite similar conformations, A and B, comprise the asymmetric unit of the title compound, C23H21N3O2S. The terminal amide substituent is coplanar with the attached benzene ring [the O—C—C—C torsion angles are 174.0 (2) (A) and 6.3 (3)° (B)]. In the same way, the central amide group [C—C—C—O = 7.8 (3) (A) and 11.5 (3)° (B)] is approximately coplanar with the ring to which it is attached. A major twist is noted between the amide and adjacent thioamide residues [C—N—C—S = −109.29 (19) (A) and −112.29 (19)° (B)]. In the crystal, supramolecular chains along [100] are formed by N—H...O and N—H...S hydrogen bonding. These are connected into a three-dimensional architecture by C—H...π and π–π interactions [inter-centroid distance = 3.9157 (12) Å].

C–O/C–S cross coupling of aryl halides with phenol or thiophenol was studied under ligand-free condition at room temperature over CuO nanocatalyst. The scope of the reaction was extended to various aryl halides and substituted phenols under optimized condition. In general, efficient, selective, and reusable heterogeneous nano CuO catalytic system has been developed for room temperature C–O and C–S Ullmann type cross coupling reactions.

Aromatic, cyclic and aliphatic amines can be treated with symmetric and asymmetric diketones and ketoesters to produce β-ketoenamines in good to excellent yields.

National Research Laboratory of Chirotechnology, Department of Chemistry, Division of Molecular and Life Science,Pohang University of Science and Tech nology, Pohang, Kyungbuk 790-784, KoreaReceived March 8, 2004Key Words : Racemization, Ruthenium, Alumina, Secondary alcohols, RecyclableThe resolution of racemic alcohols is a practical approachto the synthesis of enantiomerically pure alcohols on anindustrial scale.

The catalyst is prepared and used for the title reaction of aromatic aldehydes with nitromethane.

Unprecedented selective cleavage of the carbon-sulfur bond of the ferrocenylthiosemicarbazone moiety has been observed for the first time, resulting in the formation of mixed geometrical binuclear copper complex [(PPh(3))Cu(μ-S)(2)Cu(PPh(3))(2)]. Upon trying direct synthesis of the title complex, an unusual tetranuclear [Cu(4)(μ(3)-Cl)(4)(PPh(3))(4)] cubane resulted.

A series of norephedrine-based Schiff bases (1a-6a and 1b-6b) were synthesized by reacting substituted salicylaldehydes with d-norephedrine or l-norephedrine. The structure of these compounds was confirmed by elemental analyses and spectroscopic techniques. The molecular structures of 5a and 6a have been determined by X-ray crystallography, which revealed that the compounds are in the oxoamino form, with bent intramolecular N-H···O (N···O ≈ 2.58 Å) hydrogen bonds and that they are associated in dimers bridged by linear intermolecular O-H···O (O···O ≈ 2.69 Å) hydrogen bonds. The density functional theory calculations on 5a confirmed that the oxoamino form is more stable than the phenolimino form by 12.2 kcal/mol. All the compounds were evaluated for their antibacterial activity using resazurin dye as indicator by twofold dilution method against four bacteria namely, Bacillus subtilis (NCIM2718), Staphylococcus aureus (NCIM5021), Escherichia coli (NCIM2931), and Proteus vulgaris (NCIM2813).

New four-coordinated tetrahedral copper(I) complexes have been synthesized from the reactions between [CuCl(2)(PPh(3))(2)] and N-(diphenylcarbamothioyl)benzamide (HL1) or N-(diethylcarbamothioyl)benzamide (HL2) in benzene. These complexes have been characterized by elemental analyses, IR, UV/Vis, (1)H, (13)C and (31)P NMR spectroscopy. The molecular structure of both the complexes, [CuCl(HL1)(2)(PPh(3))] (1) and [CuCl(HL2)(PPh(3))(2)] (2) were determined by single-crystal X-ray diffraction, which reveals distorted tetrahedral geometry around each Cu(I) ion. The combination of 2 (0.005 mmol) with hydrogen peroxide (2.5 mmol) in acetonitrile is found to be an active catalyst for the oxidation of primary and secondary alcohols (0.5 mmol) to their corresponding acids and ketones, respectively, at room temperature.

The title compound, C(16)H(24)N(2)OS, is twisted about the central N(H)-C bond with the C-N-C-S torsion angle being 119.6 (3)°. The carbonyl O and thione S atoms are directed to opposite sides of the mol-ecule, a conformation that allows for the formation of a linear supra-molecular chain comprising alternating eight-membered {⋯HNCS}(2) and 14-membered {⋯HCNCNCO}(2) synthons.

In the title compound, C17H20ClN3OS, the mean plane of the central thiourea core makes dihedral angles of 26.56 (9) and 47.62 (12)° with the mean planes of the chromene moiety and the cyclohexyl ring, respectively. The cyclohexyl ring adopts a chair conformation. The N–H atoms of the thiourea unit adopt ananticonformation. The chromene group is positionedtrans, whereas the cyclohexyl ring lies in thecisposition to the thione S atom, with respect to the thiourea C—N bond. In the crystal, molecules are linked by N—H...S hydrogen bonds, forming inversion dimers enclosingR22(8) ring motifs. The dimers are linked by C—H...Cl hydrogen bonds, enclosingR66(44) ring motifs, forming sheets lying parallel to (010).

Two independent thiourea derivatives comprise the asymmetric unit of the title compound, C14H20N2OS. The major difference between the molecules relates to a twist in the relative orientation of the benzene rings [torsion angles = 4.5 (2) and −19.9 (2)° for the two independent molecules]. The thiocarbonyl and carbonyl groups lie to opposite sides of the molecule as there are twists about the central N—S bond [torsion angles = 83.90 (15) and 81.77 (15)°]. Supramolecular chains extending parallel to [101] with a stepped topology and mediated by N—H...O hydrogen bonding feature in the crystal structure. C—H...O and C—H...π interactions are also present.

Ruthenium acts as a good catalyst for the racemization reaction of secondary alcohols and amines. Ruthenium-catalyzed racemization is coupled with enzymatic kinetic resolution to prepare chiral compounds in 100% theoretical yield. Ten ruthenium complexes ( 1 – 10 ) act as a good catalyst the for racemization reaction and are also compatible with DKR process. Two other ruthenium complexes [RuCl 2 (PPh 3 ) 3 ] and [Cp ∗ RuCl(COD)] are active for racemization reaction but their successful compatibility with DKR has not yet been reported. Ru/γ-Al 2 O 3 and Ru–HAP are the heterogeneous catalysts used for the racemization reaction. They have also not been employed for DKR process. Polymer supported ruthenium is employed as a reusable racemization catalyst for aerobic DKR of alcohols.

New complexes of Pd(II) with N-substituted thiosemicarbazone (1)-(3) have been synthesised and characterised by elemental analyses, IR, electronic, (1)H NMR spectroscopies. The electrochemical behaviour of the complexes has been tested by using cyclic voltammetry. The crystal structures of the complexes have been determined by single crystal X-ray diffraction technique. In all the complexes the thiosemicarbazone ligand is coordinated to palladium through ONS mode. The complex 1 crystallises in the monoclinic space group P2(1)/c with two molecules per unit cell, has the dimensions of a=9.4390(19)A, b=10.645(2)A, c=13.668(3)A, alpha=90 degrees , beta=91.43 degrees and gamma=90 degrees . The complex 3 crystallises in the monoclinic space group P2(1)/c with four molecules per unit cell, has the dimensions of a=14.119(3)A, b=11.155(2)A, c=18.503(4)A, alpha=90 degrees , beta=112.02 degrees and gamma=90 degrees . The new complexes have been tested for their antibacterial activity against various pathogenic bacteria. From this study, it was found out that the activity of the complex 2 almost reaches the effectiveness of the conventional bacteriocide Streptomycin.

A series of N,N′,N′′-trisubstituted guanidine ligands (L1–L5) and their copper(II) complexes (1–5) [Cu(II){C4H3SCONC(NHR)NC6H5}2] [where R = p-tolyl (1), phenyl (2) benzyl (3), butyl (4) and cyclohexyl (5)] were synthesized and characterized by elemental analyses and UV-visible, FT-IR, 1H & 13C NMR/EPR and mass spectroscopic techniques. The molecular structure of L1–L5, 3, and 5 was confirmed by single crystal X-ray crystallography. The single crystal X-ray structure of the complexes reveals the square planar geometry. The interaction of calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) with the copper(II) complexes was investigated using UV-visible and fluorescence spectrophotometric methods. Spectral evidence shows the intercalative mode of DNA binding (in the order of 104 M−1) with the complexes. The Stern–Volmer quenching constant (Kq) values were found from competitive binding studies and found to be in the range of 1.07–1.30 × 105 M−1 for the complexes. Spectral evidence also shows good binding properties of the complexes with the protein. Complexes 3 and 4 showed significant cytotoxicity against human breast (MCF7) and lung cancer (A549) cell lines.

Ultrafine ruthenium oxide nanoparticles (RuO2NPs) with an average diameter of 1.3 nm were anchored on graphene nanoplatelets (GNPs) using a Ru(acac)3 precursor by a very simple dry synthesis method. The resultant material (GNPs–RuO2NPs) was used as a heterogeneous catalyst for the N-oxidation of tertiary amines for the first time. The transmission electron microscopy (TEM) images of the GNPs–RuO2NPs showed the excellent attachment of RuO2NPs on GNPs. The loading of Ru in GNPs–RuO2NPs was 2.68 wt%, as confirmed by scanning electron microscope-energy dispersive spectroscopy (SEM-EDS). The X-ray photoelectron spectrum (XPS) and the X-ray diffraction pattern (XRD) of GNPs–RuO2NPs revealed that the chemical state of Ru on GNPs was +4. After the optimization of reaction conditions for N-oxidation of triethylamine, the scope of the reaction was extended to various aliphatic, alicyclic and aromatic tertiary amines. The GNPs–RuO2NPs showed excellent catalytic activity in terms of yields even at a very low amount of Ru catalyst (0.13 mol%). The GNPs–RuO2NPs was heterogeneous in nature, chemically as well as physically, very stable and could be reused up to 5 times.

Two independent thiourea molecules comprise the asymmetric unit of the title compound, C22H20N2OS. The central N–C(=S)N(H)C(=O) atoms in each molecule are virtually superimposable and each is twisted [C—N—C—S torsion angles = 121.3 (3) and −62.3 (4)°]. The molecules differ only in terms of the relative orientations of the benzyl benzene rings [major difference between the C—N—C—C torsion angles of −146.6 (3) and −132.9 (3)°]. The presence of N—H...S hydrogen bonding leads to the formation of supramolecular chains along the a axis. These are consolidated in the crystal packing by C—H...O interactions. The crystal was found to be a combined non-merohedral and racemic twin (twin law overline{1}00/0overline{1}0/001), with the fractional contribution of the minor components being approximately 9 and 28%.

Ruthenium oxide nanorods (RuNRs) supported on graphene nanoplatelets (GNPs) were successfully prepared for the very first time by a simple “mix and heat” method, and were found to be an effective and reusable heterogeneous catalyst for the transfer hydrogenation of aromatic aldehydes and ketones in good yield with excellent selectivity.

CuO/aluminosilicate has been found to be an efficient catalyst for the aqueous Heck coupling of styrene with aryl halides under ligand free conditions. The catalyst (CuO/aluminosilicate) was prepared from CuCl2·6H2O, aluminium nitrate and tetraethyl orthosilicate (TEOS) and characterized by XRD, HR-TEM, SEM-EDX and XPS. The reaction conditions were optimized with different solvents, bases, catalyst amounts and temperatures using sytrene and 4-chlorobenzonitrile as a model system. The scope of the reaction was subsequently extended to include various substituted aryl halides. Regioselectivity, heterogeneity and reusability were performed.

The reaction of Ru3(CO)12 with N-isopropyl-2,3,4,5-tetrabutylcyclopenta-2,4-dienimine led to the formation of [2,3,4,5-Bu4(η5-C4CNHiPr)]Ru(CO)2Cl. The new complex has been characterized by 1H NMR, 13C NMR, IR and mass spectral data.

In the title salt, C14H16N+·Cl−, the complete cation and complete anion are generated by the application of mirror symmetry. The molecule is nonplanar, as seen in the dihedral angle between the terminal phenyl rings [70.92 (5)°]. In the crystal, N—H...Cl hydrogen bonds involving both azanium H atoms link the ions into a zigzag supramolecular chain along [100].

Cu/AlO(OH) has been found to be an efficient catalyst for the formation of β-enamino ketones/esters under solvent, ligand and base free conditions. The catalyst Cu/AlO(OH) is prepared from CuCl2·2H2O, pluronic P123 and Al(O-sec-Bu)3. The prepared catalyst is characterized by HR-TEM, SEM-EDX, XPS and FT-IR spectra. The β-ketoenamine is prepared using Cu/AlO(OH) as catalyst under mild and environmentally benign conditions. The reaction conditions are optimized with different catalyst amounts and temperatures using an acetylacetone and aniline system as a model. The scope of the reaction is extended to different types of diketones and amines. Solvent, ligand and base free and room temperature conditions make the reaction interesting from both an economic and environmental point of view. A mechanism is proposed on the basis of DFT calculations.

The title salt, C12H24N+·NCS−, represents a monoclinic polymorph of the previously reported orthorhombic form [Khawar Rauf et al. (2008). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their molecular structures relating to the relative dispositions of the cyclohexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding interactions, i.e. 2 × N—H...N versus N—H...N and N—H...S. The resulting supramolecular architecture is a supramolecular chain along the c axis based on a square-wave topology.

The complex mol-ecule of the title complex, [Pd(C(16)H(23)N(2)OS)(2)], is completed by crystallographic twofold symmetry with the metal atom lying on the rotation axis. The Pd(II) atom exists within a slightly distorted square-planar geometry defined by a cis-O(2)S(2) donor set. The dihedral angle formed between the mean planes of the symmetry-related six-membered chelate rings is 12.88 (7)° and the bond lengths within the rings are indicative of significant electron delocalization. In the crystal, mol-ecules aggregate into dimers linked by four C-H⋯O inter-actions.

Two independent molecules comprise the asymmetric unit of the title compound, C14H20N2OS. These differ in the relative orientations of the pentyl chains [C—C—C—C torsion angles = −176.7 (3) and 176.4 (3)°]. Significant twists are evident in each molecule, the dihedral angles formed between the thiourea and amide residues being 53.47 (17) and 55.81 (17)°. In the crystal, each molecule self-associates via a centrosymmetric eight-membered {...HNC=S}2 synthon, and these are connected into a supramolecular chain along [110] via C—H...O contacts. Disorder is noted for one of the independent molecules in that two orientations (50:50) were resolved for its benzene ring.

The Ni(II) atom in the title complex, [Ni(C(13)H(8)BrNOS)(C(18)H(15)P)], is coordinated by the N, O and S atoms of the dianionic tridentate ligand, and its square-planar geometry is completed by a phosphane P atom. The dihedral angle between the aromatic rings in the 4-bromo-2-[(2-sulfido-phen-yl)imino-meth-yl]phenolate ligand is 2.01 (14)°. The most prominent feature of the packing is the presence of supra-molecular chains aligned along the a axis, mediated by C-H⋯S inter-actions.

The title molecule, C16H24N2OS, is twisted about the central N(H)—C bond with a C—N(H)—C—N torsion angle of −62.67 (15)°. The carbonyl group is twisted out of the plane of the benzene ring, forming a C—C—C=O torsion angle of −25.06 (17)°. In the crystal, molecules related by centres of symmetry are linked by pairs of intermolecular N—H...S hydrogen bonds, forming eight-membered {...HNCS}2 synthons. These are further connected by weak via C—H...O contacts, forming a two-dimensional array in the bc plane.