Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and Bis(4-benzylpiperidine-1-carbodithioato)-lead(II) as Precursors for Lead Sulphide Nano Photocatalysts for the Degradation of Rhodamine B.

Thandi B Mbuyazi,Peter A Ajibade

doi:10.3390/molecules26237251

Thandi B Mbuyazi, Peter A Ajibade

Open Access

https://doi.org/10.3390/molecules26237251

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Journal: Molecules (Basel, Switzerland)	Publication Date: Nov 29, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: University of KwaZulu-Natal

Abstract

Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and bis(4-benzylpiperidine-1-carbodithioato)-lead(II) were prepared and their molecular structures elucidated using single crystal X-ray crystallography and spectroscopic techniques. The compounds were used as precursors for the preparation of lead sulphide nano photocatalysts for the degradation of rhodamine B. The single crystal structures of the lead(II) dithiocarbamate complexes show mononuclear lead(II) compounds in which each lead(II) ion coordinates two dithiocarbamato anions in a distorted tetrahedral geometry. The compounds were thermolyzed at 180 ℃ in hexadecylamine (HDA), octadecylamine (ODA), and trioctylphosphine oxide (TOPO) to prepare HDA, ODA, and TOPO capped lead sulphide (PbS) nanoparticles. Powder X-ray diffraction (pXRD) patterns of the lead sulphide nanoparticles were indexed to the rock cubic salt crystalline phase of lead sulphide. The lead sulphide nanoparticles were used as photocatalysts for the degradation of rhodamine B with ODA-PbS1 achieving photodegradation efficiency of 45.28% after 360 min. The photostability and reusability studies of the as-prepared PbS nanoparticles were studied in four consecutive cycles, showing that the percentage degradation efficiency decreased slightly by about 0.51–1.93%. The results show that the as-prepared PbS nanoparticles are relatively photostable with a slight loss of photodegradation activities as the reusability cycles progress.

Highlights

Lead sulphide (PbS) nanomaterials are IV-VI semiconductor compounds with a large excitonic Bohr radius of 18 nm and narrow band gap of 0.41 eV at ambient temperature (300 K) [1]
The v(–NCS2) frequency observed at 1468 cm−1 and 1469 cm−1 in the 4-methylpiperidine dithiocarbamate (Mpipdtc) and 4-benzylpiperidine dithiocarbamate (Bpipdtc) ligands shifted to 1429 cm−1 and 1478 cm−1 in [Pb(4-mpipdtc)2] and [Pb(4-Bpipdtct)2] complexes
The compounds were thermolyzed at 180 °C to prepare hexadecylamine (HDA), octadecylamine (ODA), and trioctylphosphine oxide (TOPO) capped lead sulphide (PbS) nanoparticles. powder X-ray diffraction (pXRD) showed that the nanoparticles are in the cubic rock salt phase of PbS

Summary

Introduction

Lead sulphide (PbS) nanomaterials are IV-VI semiconductor compounds with a large excitonic Bohr radius of 18 nm and narrow band gap of 0.41 eV at ambient temperature (300 K) [1]. The v(–NCS2) frequency observed at 1468 cm−1 and 1469 cm−1 in the 4-methylpiperidine dithiocarbamate (Mpipdtc) and 4-benzylpiperidine dithiocarbamate (Bpipdtc) ligands shifted to 1429 cm−1 and 1478 cm−1 in [Pb(4-mpipdtc)2] and [Pb(4-Bpipdtct)2] complexes. This band lies between the C-N single bond and double bond characters and confirmed bonding of the dithiocarbamato anions to the Pb(II) ions [26,27]. The free ligands spectra showed single sharp bands due to ν(C−S) at 946 cm−1 for 4-methylpiperidine dithiocarbamate and 945 cm−1 for 4-benzylpiperidine dithiocarbamate These bands shifted to 959 cm−1 and 961 cm−1 in their respective Pb(II) complexes. The Pb(II) complexes both exhibit bands at 265 nm due to charge transfer transitions, which is consistent with Pb(II) complexes [30]

Powder X-ray Diffraction Studies of the PbS Nanoparticles

Photocatalytic Studies

X-ray Crystallography

Preparation of PbS Nanoparticles

Photodegradation of Rhodamine B Dye

Findings

Conclusions