Synthesis, Structure and Light-Harvesting Properties of Some New Transition-Metal Dithiocarbamates Involving Ferrocene

Antiproliferative activity of Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of dithiocarbamate: synthesis, structural characterization, and thermal studies

Five new metal complexes of Fe(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4), and Zn(II) (5), derived from an N-cyclohexyl N-(3,4-dimethoxybenzyl) dithiocarbamate ligand, have been successfully synthesized and fully characterized by different analytical techniques i.e. elemental analyses, FT-IR, UV-Vis, 1H & 13C NMR, and HRMS. Furthermore, complexes 4 and 5 have been characterized by the SC-XRD technique. Complex 4 adopts a distorted square planar geometry around the Cu(II) center while complex 5 adopts a distorted tetrahedral geometry around the Zn(II) center. In addition, an eight-membered symmetric chair-like metallacycle ring containing two Zn(II) centers has also been found in complex 5. XRD data also show that complexes 4 and 5 are stabilized by various weak intermolecular hydrogen bonding interactions. The course of the thermal degradation of metal complexes 1-5 has been examined by TG-DTA data which revealed that metal sulphide formed as the final residue. Complexes 1-5 demonstrated concentration-dependent cytotoxicity and growth inhibition of DL tumor cells. Among the compounds, complexes 1, 4, and 5 showed significant cytotoxicity and induced a loss in the viability of DL cells. Therapy with complexes 1, 4, and 5 protects DL tumor-bearing animals from exacerbation of the disease, increases lifespan, and significantly improves the histopathological parameters of the vascularized organ, including preventing metastasis. Overall cytotoxicity assay results indicate that all complexes have remarkable cytotoxic potential in comparison with the free ligand.

A double co-sensitization strategy using heteroleptic transition metal ferrocenyl dithiocarbamate phenanthrolene-dione for enhancing the performance of N719-based DSSCs

Three new heteroleptic dithiocarbamate complexes with formula [M(Phen-dione)(Fcdtc)]PF6 (where M = Ni(ii) Ni-Fc, Cu(ii) Cu-Fc) and [Co(Phen-dione)(Fcdtc)2]PF6 (Co-Fc) (Fcdtc = N-ethanol-N-methylferrocene dithiocarbamate and Phen-dione = 1,10-phenanthroline-5,6-dione; PF6 - = hexafluorophosphate) were synthesized and characterized using microanalysis, FTIR, electronic absorption spectroscopy and mass spectrometry. The solution state electronic absorption spectroscopy for all three complexes displayed a band at ∼430 nm corresponding to the ferrocene unit and another low-intensity band in the visible region arising because of the d-d transitions. These newly synthesized complexes were used as co-sensitizers for the state-of-the-art di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(ii) (N719) dye in dye-sensitized solar cells (DSSCs). Among the three co-sensitizers/co-adsorbent-based DSSC set-ups, the assembly fabricated using Co-Fc/N719 displayed good photovoltaic performance with 5.31% efficiency (η) while a new triple component strategy inculcating N719, Co-Fc and Cu-Fc dyes offered the best photovoltaic performance with 6.05% efficiency (η) with incident photon to current conversion efficiency (IPCE) of 63%. This indicated an upliftment of the DSSC performance by ∼38% in comparison to the set-up constructed by employing only N719 dye (η = 4.39%) under similar experimental conditions.

New di-n-butyltin(iv)-bis-(1-alkoxy-isoquinoline-4-nitrile thiolate): crystallographic and computational studies

Alcohol and n-Bu2Sn2+ assisted cyclization of dithiolate yielded two unexpected organotin(iv) products, their reaction mechanism and nature of weak interactions assessed.

Inorganic Pb(II)-P and Pb(II)-S Complexes as Photosensitizers from Primary and Secondary Amines in Dyes-Sensitized Solar Cells

Pb(II) complexes of bis(N-1,4-phenyl-N-(4-morpholinedithiocarbamato)) as Pb(II)-S and bis(N-diisopropyl-N-octyldithiocarbamato) as Pb(II)-P were prepared and characterized by optical, structural, morphological, and electrochemical techniques. The scanning electron microscopy analysis of Pb(II)-P and Pb(II)-S complexes consists of cubic crystals. X-ray diffraction and high-resolution transmission electron microscopy spectral studies revealed that the diameter increases in length for alkyl chain groups. This study demonstrates that the cubic shape of Pb(II) complexes can be synthesized from aromatic and aliphatic dithiocarbamate ligands. Photoluminescence analysis of both complexes fell within the blue shift region. The CV curve for Pb(II)-S revealed redox curves and the box-like shape as an indicative of a capacitive behavior, signifying limited catalytic redox activity. The J-V results for both sensitizers displayed satisfactory conversion efficiency (% η) between 3.77 and 3.96%.

Similar, Yet Different: Long-Range Metal-Metal Coupling and Electron-Transfer Processes in Metal-Free 5,10,15,20-Tetra(ruthenocenyl)porphyrin

The electronic structure, redox properties, and long-range metal-metal coupling in metal-free 5,10,15,20-tetra(ruthenocenyl)porphyrin (H₂TRcP) were probed by spectroscopic (NMR, UV-vis, magnetic circular dichroism (MCD), and atmospheric pressure chemical ionization (APCI)), electrochemical (cyclic voltammetry, CV, and differential pulse voltammetry, DPV), spectroelectrochemical, and chemical oxidation methods, as well as theoretical (density functional theory, DFT, and time-dependent DFT, TDDFT) approaches. It was demonstrated that the spectroscopic properties of H₂TRcP are significantly different from those in H₂TFcP (metal-free 5,10,15,20-tetra(ferrocenyl)porphyrin). Ruthenocenyl fragments in H₂TRcP have higher oxidation potentials than the ferrocene groups in the H₂TFcP complex. Similar to H₂TFcP, we were able to access and spectroscopically characterize the one- and two-electron oxidized mixed-valence states in the H₂TRcP system. DFT predicts that the porphyrin π-system stabilizes the [H₂TRcP]⁺ mixed-valence cation and prevents its dimerization, which is characteristic for ruthenocenyl systems. However, formation of the mixed-valence [H₂TRcP]²⁺ is significantly less reproducible than the formation of [H₂TRcP]⁺. DFT and TDDFT calculations suggest the ruthenocenyl fragment dominance in the highest occupied molecular orbital (HOMO) energy region and the presence of the low-energy MLCT (Rc → porphyrin (π*)) transitions in the visible region with energies higher than the predominantly porphyrin-centered Q-bands.

Ferrocene-Functionalized Dithiocarbamate Zinc(II) Complexes as Efficient Bifunctional Catalysts for the One-Pot Synthesis of Chromene and Imidazopyrimidine Derivatives via Knoevenagel Condensation Reaction

Four new mononuclear/coordination polymeric (CP) zinc(II) complexes (1-4) of ferrocenyl/pyridyl-functionalized dithiocarbamate ligands, N-ferrocenylmethyl-N-butyl dithiocarbamate (L1), N-ferrocenylmethyl-N-ethylmorpholine dithiocarbamate (L2), N-ferrocenylmethyl-N-2-(diethylamino)ethylamine dithiocarbamate (L3), and N-4-methoxybenzyl-N-3-methylpyridyl dithiocarbamate (L4), have been synthesized and characterized by elemental analyses, IR, UV-vis, and ¹H and ¹³C{¹H} NMR spectroscopic techniques. The solid-state structures of complexes 1, 3, and 4 have been determined by single-crystal X-ray crystallography as well as powder X-ray diffraction. Single-crystal X-ray crystallography revealed a monomeric structure for complex 1 but 1D polymeric structures for complexes 3 and 4. In all complexes, dithiocarbamate ligands are bonded to the Zn(II) metal ion in a S^S chelating mode, and in the CPs, N atoms on the 2-(diethylamino)ethylamine and 3-pyridyl functionalities in the ligands on the neighboring molecules are also bonded to metal centers, leading to the formation of either a discrete tetrahedral molecule in 1 or 1D CP structures in 3 and 4. The Zn(II) metal centers in the polymeric structures exhibited either square-pyramidal or octahedral geometries. The supramolecular structures in these complexes are sustained via C-H···π (ZnCS₂, chelate; 3 and 4), C-H···π, and H···H interactions. The catalytic performances of complexes have also been assessed in the Knoevenagel condensation and one-pot multicomponent reactions. Catalysis results showed that the CP 3 acts as a heterogeneous bifunctional catalyst with excellent transformation efficiency at low catalyst loading.

Ferrocene decorated unusual mercury(ii) dithiocarbamate coordination polymers: crystallographic and computational studies

Three new ferrocene decorated 1D coordination polymers of Hg(ii) dithiocarbamates were synthesized and the nature of their weak interactions was addressed using computational techniques.

Computational studies of Ni(II) photosensitizers complexes containing 1,1′-bis(diphenylphosphino)ferrocene and dithio ligands

Detailed theoretical studies of Ni(II) complexes in a distorted square planar form and containing dithio and (P, P) chelating ligands were performed. These Ni(II) complexes are investigated for their use in dye-sensitized solar cells (DSSC). Structures and UV–vis spectra are calculated at density functional theory (DFT) and time-dependent density functional theory (TD-DFT) theories using B3LYP and CAM-B3LYP functionals and 6-31G(d,p) and 6-31G+(d) basis sets. Geometry optimizations result in excellent agreement with the experimental results. Moreover, the analysis of the frontier molecular orbitals (FMOs) allowed a detailed assignment and a clear analysis of the electronic transitions. The TD-DFT calculations reproduce the main spectroscopic properties observed and substituent effects. The results reveal that all absorption spectra are characterized by mixed character mainly dominated by metal to ligand and ligand to ligand charge transfers (MLCT and LLCT). We unveil how the substituent variations affect the DSSCs features of the complexes.

The remarkable propensity for the formation of C–H⋯π(chelate ring) interactions in the crystals of the first-row transition metal dithiocarbamates and the supramolecular architectures they sustain

C–H⋯π(chelate ring) interactions play an important role in assembling first-row transition metal dithiocarbamates in their crystals.

New main-group ferrocenyldithiocarbamates and conversion to ferrocene oxazolidine-2-thione and -2-one

Three new main-group ferrocenyl dithiocarbamates and a pure cyclised product, 3-ferrocenylmethyl-oxazolidine-2-thione, were isolated using copper powder.

New 1D diorganotin(iv) dithiolate coordination polymers: crystallographic, computational, Hirshfeld surface and thermal analyses

Three new 1D coordination polymers of diorganotin(iv) dithiolates synthesized and the nature of their weak interactions addressed using computational techniques.

Ferrocenylethenyl-substituted oxadiazoles with phenolic and nitro anchors as sensitizers in dye sensitized solar cells

Ferrocenylethenyl-substituted oxadiazoles with phenolic and nitro anchors were synthesized and used as sensitizers in dye sensitized solar cells (DSSCs).

Highly efficient structurally characterised novel precatalysts: di- and mononuclear heteroleptic Cu(i) dixanthate/xanthate–phosphine complexes for azide–alkyne cycloadditions

Prominent catalytic activities of novel di- and mononuclear Cu(i) xanthate/phosphine complexes have been investigated for the synthesis of triazolyl glycoconjugates using Click approach.

Exploring the Topological Landscape Exhibited by Binary Zinc-triad 1,1-dithiolates

The crystal chemistry of the zinc-triad binary 1,1-dithiolates, that is, compounds of xanthate [−S2COR], dithiophosphate [−S2P(OR)2], and dithiocarbamate [−S2CNR2] ligands, is reviewed. Owing to a wide range of coordination modes that can be adopted by 1,1-dithiolate anions, such as monodentate, chelating, μ2-bridging, μ3-bridging, etc., there exists a rich diversity in supramolecular assemblies for these compounds, including examples of zero-, one-, and two-dimensional architectures. While there are similarities in structural motifs across the series of 1,1-dithiolate ligands, specific architectures are sometimes found, depending on the metal centre and/or on the 1,1-dithiolate ligand. Further, an influence of steric bulk upon supramolecular aggregation is apparent. Thus, bulky R groups generally preclude the close approach of molecules in order to reduce steric hindrance and therefore, lead to lower dimensional aggregation patterns. The ligating ability of the 1,1-dithiolate ligands also proves crucial in determining the extent of supramolecular aggregation, in particular for dithiocarbamate species where the relatively greater chelating ability of this ligand reduces the Lewis acidity of the zinc-triad element, which thereby reduces its ability to significantly expand its coordination number. Often, the functionalisation of the organic substituents in the 1,1-dithiolate ligands, for example, by incorporating pyridyl groups, can lead to different supramolecular association patterns. Herein, the diverse assemblies of supramolecular architectures are classified and compared. In all, 27 structurally distinct motifs have been identified.

1,1′-Bis(diphenylphosphino)ferrocene-appended nickel(ii) dithiolates as sensitizers in dye-sensitized solar cells

Herein, two dppf-appended Ni(ii) dithiolates with 2,2-diacetyl and 2-nitro anchors were prepared, and their light harvesting properties were explored in dye-sensitized solar cells (DSSCs).

Cooperative metal–ligand influence on the formation of coordination polymers, and conducting and photophysical properties of Tl(i) β-oxodithioester complexes

Eight novel luminescent and semiconducting Tl(i) β-oxodithioester complexes forming 1D/2D coordination polymeric structures were investigated using single crystal X-ray diffraction.

Ferrocenyl benzimidazole with carboxylic and nitro anchors as potential sensitizers in dye-sensitized solar cells

Two ferrocenyl benzimidazoles with carboxylic and nitro anchors were prepared and their light harvesting properties explored in dye-sensitized solar cells (DSSCs).

(D–π–A)2–π–D–A type ferrocenyl bisthiazole linked triphenylamine based molecular systems for DSSC: synthesis, experimental and theoretical performance studies

We have designed and synthesized ferrocenyl (donor) bisthiazole linked triphenylamine (donor) based (D–π–A)₂–π–D–A type dyes D1 and D2 for DSSCs.

A ferrocenecarboxylate-functionalized titanium-oxo-cluster: the ferrocene wheel as a sensitizer for photocurrent response

A ferrocenecarboxylate-functionalized titanium-oxo cluster [Ti₆(μ₃-O)₆(OiPr)₆(O₂CFc)₆] was synthesized, in which the ferrocene wheel performs as a sensitizer for photocurrent response.

Bis[bis(N-2-hydroxyethyl,N-isopropyl-dithiocarbamato)mercury(II)]2: crystal structure and Hirshfeld surface analysis

The presence of both κ2-chelating and μ2,κ2-tridentate bridging dithiocarbamate ligands in centrosymmetric {Hg[S2CN(iPr)CH2CH2OH]2}2 (1) leads to globular aggregates that are linked into a three-dimensional architecture via hydroxyl-O–H···O(hydroxy) hydrogen bonding. The structure contrasts that of Hg[S2CN(CH2CH2OH)2]2 (2; this is a literature structure) in which square planar units are connected into supramolecular chains via Hg···S secondary bonding; chains are connected in the crystal structure by hydroxyl-O–H···O(hydroxy) hydrogen bonding. A Hirshfeld surface analysis on 1 and 2 reveal the influence of O–H···O and Hg···S interactions on the molecular packing as well as the distinctive interactions, such as C–H···S interactions in 1 and C–H···π (HgS2C) contacts in 2. A bibliographic survey shows the different structural motifs observed for 1 and 2 are complimented by an additional five motifs for binary mercury(II) dithiocarbamates revealing a fascinating structural diversity for this class of compound.