Sudhir Ranjan

SYNTHESIS, SPECTROSCOPIC, PHOTOPHYSICAL AND ELECTROCHEMICAL PROPERTIES OF CYANO-BRIDGED COPPER(I)-RUTHENIUM(II) COMPLEXES

Abstract Complexes of the formula [(N–N)Cu(AsPh 3 )CN] (N–N=2,2′–bipyridine, 1,10–phenanthroline) have been synthesized. Ru(bpy) 2 Cl 2 .2H 2 O and [( η 5 –cp)Ru(PPh 3 ) 2 Cl] react with [(N–N)Cu(AsPh 3 )CN] to give cyano-bridged compounds. IR spectral studies in the low frequency region (700–50 cm −1 ) and 4000–400 cm −1 region reveal cyano bridging in the complexes. Luminescence measurements suggest oxidation of metal centres (Cu I –Cu II and Ru II –Ru III ) on excitation at a charge transfer band. This has been substantiated with electrochemical studies of complexes which exhibit quasi-reversible reductions viz. Ru III ⧹Ru II and Cu II ⧹Cu I . The deposition of metallic copper is also observed at a potential of −1.55 V. Based on these data, a mechanism for photo-redox reaction of complexes has been presented. The properties of these bimetallic complexes are compared with those of parent complexes.

Synthesis, spectroscopic, photophysical and electrochemical behaviour of ruthenium(II) and copper(I) isocyano-bridged complexes with polypyridine ligands: 2,2′-bipyridine and 1,10-phenanthroline

New binuclear complexes with [Cu(PPh3)3]+ and [Cu(PPh3)(N—N)]+ (N—N – 2,2′-bipyridine, 1,10-phenanthroline) moieties connected via the isocyanide group to [Ru(bpy)2(py)]+ and [Ru(phen)2(py)]+ have been prepared and isolated as PF6− salts. In addition, new trinuclear complexes, [{(PPh3)3Cu(μ-NC)}2Ru(bpy)2](PF6)2 and [{(N—N)-(PPh3)Cu(μ-NC)}2Ru(bpy)2](PF6)2, have been synthesized using [Ru(bpy)2(CN)2]. The complexes have been characterized by elemental analyses, i.r., n.m.r., u.v.–vis., FAB mass spectra and by conductivity measurements. The i.r. spectra reveal an increase in v;(CN) in the isocyano-bridged complexes compared to the mononuclear parent complexes. The complexes are luminescent with emission wavelengths in the 458–550 and 600–636 nm ranges. The half wave reduction potentials in MeCN are always more positive than those of the parent complexes. It is observed that the isocyano-bridged complexes are more powerful excited state reductants than the cyano-bridged, Cu(I)(μ-CN)Ru(II) complexes.

Synthesis and Characterization of Mixed- Ligand Complexes of Cu(I) Containing Halides, Triphenylstibine and Triphenylbismuthine, N,N-Dimethyl-N′-Phenylthiourea (Dmpth), N,N-Dibutyl-N′-Phenylthiourea (dbptH) and 1,3-thiazolidine-2-thione (tzdtH)

Abstract The triphenylstibine and bismuthine complexes [Cu(EPh3)(LH)2X] (LH = N, N-dimethyl-N′-phenylthiourea) (dmptH), N, N-dibutyl-N′-phenylthiourea (dbptH) or 1, 3-thiazolidine-2-thione (tzdtH); E = Sb or Bi; X = Cl, Br or I have been prepared and characterized on the basis of analytical, IR. electronic (UV-Vis), 1H and I3C NMR, FAB mass and conductivity measurements. In all cases there is a distorted tetrahedral environment around Cu(I) and the ligand (LH) binds through the thionc sulphur atom to copper(1). This is confirmed by FTIR spectra of the complexes. The complexes show v(Cu-Sb) in the range 180–195 cm−1.

Multi-walled Carbon Nanotube/Polymer Composite: A Nano-enabled Continuous Fiber

A homogeneous mixture of poly(vinyl alcohol) (PVA), poly(ethylene-co-vinyl alcohol) (EVOH) and multi-walled carbon nanotubes (MWCNTs) was prepared. A nano-enabled composite fiber was continuously spun using this homogeneous mixture through a single-hole spinneret into a coagulation bath containing methanol. The physical properties and the intermolecular interactions of the fiber were studied by scanning electron microscopy, optical microscopy, thermal gravimetric analysis, and infrared spectroscopy. Fourier transform infrared analysis suggests that there is an interfacial interaction between PVA, EVOH, and MWCNT through the functional groups attached to them along the molecular chains of the fibers. Tensile strength was measured. The careful removal of a small amount of PVA produced a 20% increase in tensile strength.

Synthesis and Characterization of Mixed-Ligand Ruthenium(II) Carbonyl Complexes Containing (Ci, Br Or I), N,N-Dimethyl-N′-Phenylthiourea (Dmpth) and 1,3-Thiazolidine-2-Thione (Tzdth)

Abstract The reactions of cis-[Ru(CO)2X2]n, (X = CI, Br or I) with ligands (I.H),N,N-dimethyl-N′-phenylthiourea (dmptH) and 1,3-thiazolidine-2-thione (tzdtH), yield [Ru(CO)2X2(LH)2]. These complexes have been characterized by analytical, conductivity, IR, electronic (UV-Vis), 1H and 13C NMR, and FAB mass spectroscopic studies. Low-frequency IR spectra (FTIR) reveal that the ligands (LH) bind through the thione sulphur atom to ruthenium. In all cases a distorted octahedral environment of a cis, cis, cis-structure is suggested.