Synthesis, Structural and Optical Properties of TOPO and HDA Capped Cadmium Sulphide Nanocrystals, and the Effect of Capping Ligand Concentration

Abstract

The thermal decomposition of bis(N,N-diallyldithiocarbamato)Cd(II) in a “one-pot” synthesis in tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) afforded CdS (TOPO-CdS and HDA-CdS) of varying optical properties and morphologies. The influence of the ratio of the precursor concentration to the capping molecule, as a factor affecting the morphology and size of the nanoparticles, was investigated. The particles varied in shape from spheres to rods and show quantum size effects in their optical spectra with clear differences in the photoluminescence (PL) spectra. The PL spectrum of the HDA capped CdS nanoparticles has an emission maximum centred at 468, 472, and 484 nm for the precursor to HDA concentration ratio of 1 : 10, 1 : 15, and 1 : 20, respectively, while the TOPO capped nanoparticles show emission peaks at 483, 494, and 498 nm at the same concentration ratio. Powdered X-ray diffraction (p-XRD) shows the nanoparticles to be hexagonal. The crystallinity of the nanoparticles was evident from high resolution transmission electron microscopy (HRTEM) which gave well-defined images of particles with clear lattice fringes.

Organotin(IV) Dithiocarbamate Complexes: Chemistry and Biological Activity

“…The υ(C-S) stretching vibrational band often appears in the 950–1000 cm −1 region, while the υ(M-S) stretching vibration band is found in the 350–450 cm −1 [ 59 ]. The movement of the C-N vibrational band after complexation with a metal to a higher frequency of about 15 cm −1 often indicates the delocalization of the electron cloud of the –NCSS group towards the metal center [ 60 ]. Thus, giving the C-N bond a partial double bond character [ 61 ].…”

Role of the amine and phosphine groups in oleylamine and trioctylphosphine in the synthesis of copper chalcogenide nanoparticles

“…It is therefore important to choose a good capping molecule that does not bond too strongly to the precursors as this would prevent particles from growing. The capping molecule should not have too weak bonds with the precursors either as the particles would grow bigger [ 9 ]. Due to this complexity, a general survey of capping agents in nano catalysis is therefore necessary [ 12 ].…”

“…The capping molecules such as trioctylphosphine (TOP) and oleylamine (OLA) can be used as solvents, reducing agents and stabilizers [ 9 , 11 , 13 , 14 ]. They provide good interaction and they can be used at higher temperatures due to their high boiling points [ 15 ].…”

“…Trioctylphosphine is a long chain alkyl phosphine (C 24 H 51 P) that uses its phosphine group (PR 3 ) [ 16 ] for interaction whereas oleylamine is a long-chain primary alkyl amine that uses its amine group (NH 2 - ) for interaction [ 15 ]. The increased proton affinity of phosphines is due to the stabilization of phenyl phosphonium ion by Л donation from phenyl group to the empty orbitals of phosphorus in the PR 3 group, in contrast, the amines are rather stabilized by conjugation of nitrogen lone pair with the aromatic ring [ 9 ]. Generally, amine group has higher affinity for protons than phosphine due to the lone pair of electrons it possesses which it easily donates to H+ compared to phosphine.…”

Bis(μ-N,N-diallyldithiocarbamato)bis[(N,N-diallyldithiocarbamato)cadmium]

“…A solution of CdCl 2 Á2H 2 O (0.55 g, 0.0025 mol) in ethanol (10 ml) was added to a solution of sodium N,N-diallyl dithiocarbamate (0.98 g, 0.005 mol) in ethanol (10 ml), and the resulting suspension was stirred for 45 min at room temperature. This solution was then filtered, and rinsed several times with distilled water (Onwudiwe et al, 2015) 14106 Table 3 X-HÁ Á Á interactions.…”