Elif Subasi

Ruthenium (II) complexes of thiosemicarbazone: synthesis, biosensor applications and evaluation as antimicrobial agents.

A conformationally rigid half-sandwich organoruthenium (II) complex [(η(6)-p-cymene)RuClTSC(N-S)]Cl, (1) and carbonyl complex [Ru(CO)Cl(PPh3)2TSC(N-S)] (2) have been synthesized from the reaction of [{(η(6)-p-cymene)RuCl}2(μ-Cl)2] and [Ru(H)(Cl)(CO)(PPh3)3] with thiophene-2-carboxaldehyde thiosemicarbazon (TSC) respectively and both novel ruthenium (II) complexes have been characterized by elemental analysis, FT-IR and NMR spectroscopy. The peripheral TSC in the complexes acts as an electrochemical coupling unit providing the ability to carry out electrochemical deposition (ED) and to form an electro-deposited film on a graphite electrode surface. The biosensing applicability of complexes 1 and 2 was investigated by using glucose oxidase (GOx) as a model enzyme. Electrochemical measurements at -0.9V versus Ag/AgCl electrode by following the ED Ru(II) reduction/oxidation due to from the enzyme activity, in the presence of glucose substrate. The designed biosensor showed a very good linearity for 0.01-0.5mM glucose. The in vitro antimicrobial activities of complexes 1 and 2 were also investigated against nine bacterial strains and one fungus by the disc diffusion test method. No activity was observed against the Gram-negative strains and fungus, whereas complex 1 showed moderate antibacterial activities against Gram-positive bacterial strains.

Combining anti-cancer drugs with artificial sweeteners: synthesis and anti-cancer activity of saccharinate (sac) and thiosaccharinate (tsac) complexes cis-[Pt(sac)2(NH3)2] and cis-[Pt(tsac)2(NH3)2].

The new platinum(II) complexes cis-[Pt(sac)2(NH3)2] (sac=saccharinate) and cis-[Pt(tsac)2(NH3)2] (tsac=thiosaccharinate) have been prepared, the X-ray crystal structure of cis-[Pt(sac)2(NH3)2] x H2O reveals that both saccharinate anions are N-bound in a cis-arrangement being inequivalent in both the solid-state and in solution at room temperature. Preliminary anti-cancer activity has been assessed against A549 human alveolar type-II like cell lines with the thiosaccharinate complex showing good activity.

Photochemical reactions of metal carbonyls [M(CO)6 (M=Cr, Mo, W)] with N , N′ -bis(salicylidene)-1,2-bis- ( o -aminophenoxy)ethane

The complexes [M(CO)4(η2-H2L)] [M = Cr; 1, Mo; 2, W; 3] have been synthesized by photochemical reactions of VIB metal carbonyls [M(CO)6] [M = Cr, Mo, W] with N,N′-bis(salicylidene)-1,2-bis-(o-aminophenoxy)ethane (H2L) in THF and characterized by elemental analyses, FTIR, 1H NMR and mass spectra. The H2L ligand is coordinated to the central metal as a bidentate ligand via the central azomethine nitrogen atoms in 1–3.

Synthesis, structural characterization, oxygen sensitivity, and antimicrobial activity of ruthenium(II) carbonyl complexes with thiosemicarbazones

[Ru(CO)(PPh3)2(η3-O,N3,S-TSC1)] (1), [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC2)] (2), and [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC3)] (3) have been prepared by reacting [Ru(H)(Cl)(CO)(PPh3)3] with the respective thiosemicarbazones TSC1 (2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone), TSC2 (3-hydroxybenzaldehyde thiosemicarbazone), and TSC3 (3,4-dihydroxybenzaldehyde thiosemicarbazone) in a 1 : 1 M ratio in toluene and all of the complexes have been characterized by UV–vis, FT-IR, and 1H and 31P NMR spectroscopy. The spectroscopic studies showed that TSC1 is coordinated to the central metal as a tridendate ligand coordinating via the azomethine nitrogen (C=N), phenolic oxygen, and sulfur to ruthenium in 1, whereas TSC2 and TSC3 are coordinated to ruthenium as a bidentate ligand through azomethine nitrogen (C=N) and sulfur in 2 and 3. Oxygen sensitivities of 1–3 and [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC4)] (4), and antimicrobial activities of 1–3 have been determined. Graphical Abstract Ru(II) carbonyl complexes were prepared by reacting [Ru(H)(Cl)(CO)(PPh3)3] with the respective thiosemicarbazone ligands and the complexes were characterized by UV–vis, FT-IR, and 1H and 31P NMR spectroscopy. Oxygen sensitivities and antimicrobial activities of the complexes were determined.

Photochemical Complexation Reactions of M(CO)6 (M=Cr, Mo, W) and Re(CO)5Br with Rhodanine (4‐Thiazolidinone‐2‐thioxo) and 5‐Substituted Rhodanines

The new complexes [M(CO)5‐DABRd] [M=Cr; 1, Mo; 2, W; 3], [cis‐Re(CO)4Br‐DABRd] (4), [M(CO)5‐BRd] [M=Cr; 5, Mo; 6, W; 7] and [Mo(CO)5‐L] [L=Rd, 8; 2CBRd, 9; 2HNARd, 10; IBRd, 11] have been synthesized by the photochemical reactions of VIB and VIIB group metal carbonyls [M(CO)6] [M=Cr, Mo, W] and [Re(CO)5Br] with 5‐(4‐dimethylaminobenzylidene)rhodanine (DABRd), 5‐benzylidenerhodanine (BRd), rhodanine (Rd), 5‐(2‐chlorobenzylidene)rhodanine (2CBRd), 5‐(2‐hydroxynaphtylidene)rhodanine (2HNARd), 5‐(4‐isopropylbenzylidene)rhodanine (IBRd) and characterized by elemental analysis, FT‐IR, 1H and 13C‐{1H}‐NMR spectroscopy and by Mass spectrometry. The spectroscopic studies show that all rhodanine ligands act as monodentate ligands coordinating via the sulfur (C˭S) donor atom in (1–11).

Synthesis and Characterization of Stable Hetereocyclic (Schiff Base) Divalent Tin Species and Photogeneration of Their Transition Metal Carbonyl Complexes

New stable divalent heterocyclic species [SnL1; 1, SnL2; 2] using ONNO and SNNS tetradentate Schiff bases; N,N′-bis(salicylidene)-1,2-bis(o-aminophenoxy)ethane (H2L1) and N,N′-bis(2-aminothiophenol)-1,4-bis(2-carboxaldehydephenoxy)butane (H2L2) were obtained in good yields by alcolysis of the M-N bonds of the divalent precursor Sn[N(SiMe3)2]2 by diols. They have been isolated as solids at ambient temperature and are monomeric. FT-IR, 1H and 119Sn-NMR spectra are suggestive of N … M intramolecular coordination. Then the synthesis and characterization of the new stable mono and cis-disubstituted Sn(II) chromium and tungsten carbonyl complexes [L1Sn]M(CO)5 (M= Cr, 3; W, 4); [L2Sn]M(CO)5 (M= Cr, 5; W, 6); cis-[L1Sn]2M(CO)4 (M= Cr, 7; W, 8) and cis-[L2Sn]2M(CO)4 (M= Cr, 9; W, 10) are described. Pentacarbonyl complexes (3–6) were obtained in high yields by treatment of the M(CO)5THF (M= Cr, W) intermediates with the divalent species [SnL1; 1, SnL2; 2] and tetracarbonyl complexes (7–10) were synthesized by the photochemical reactions of [LnSn]M(CO)5 with [LnSn] (n = 1, 2). Each of the new carbonyl complexes has been characterized by IR, 1H, 13C, 119Sn-NMR spectroscopy, and mass spectrometry. The sigma donor and pi acceptor ability of the divalent tin species [SnL1, 1; SnL2, 2] as ligands in the transition metal carbonyl complexes (3–10) is discussed by comparing ν(CO) stretching frequencies.

Photochemical reactions of Re(CO)5Br with Ph2P(S)(CH2)nP(S)Ph2 (n = 1,2,3)

The complexes fac-[Re(CO)3Br{Ph2P(S)(CH2)nP(S)Ph2}] [1a, n = 1; 2a, n = 2; 3a, n = 3] and [Re2(CO)8Br2{μ- Ph2P(S)(CH2)nP(S)Ph2}] [1b, n = 1; 2b, n = 2; 3b, n = 3] have been prepared by the photochemical reaction of Re(CO)5Br with Ph2P(S)(CH2)nP(S)Ph2. The products have been characterized by elemental analysis, mass spectroscopy, FT-IR and 31 P-[1H]-NMR spectrometry. The results suggest cis-chelate bidentate coordination of the ligand in fac-1a - 3a and cis-bridging bidentate coordination of the ligand between two metals in 1b - 3b.

Photochemical reactions of metal carbonyls with heteroaromatic methanesulfonylhydrazone-based ligands

Three new heteroaromatic methanesulfonylhydrazone derivatives: thiophene-2-carboxy aldehydemethanesulfonylhydrazone (msh 1), 2-acetylthiophenemethanesulfonylhdrazone (msh 2), and 2-acetyl-5-methylthiophenemethanesulfonylhydrazone (msh 3) were prepared and their metal carbonyl complexes ([M(CO)5(msh 1)] M = Cr, 1a; Mo, 1b; W, 1c); ([M(CO)5(msh 2)] M = Cr, 2a; Mo, 2b; W, 2c); and ([M(CO)5(msh 3)] M = Cr, 3a; Mo, 3b; W, 3c) were synthesized by photochemical reactions of [M(CO)6 M = Cr, Mo, W] with msh 1–3. Heteroaromatic methanesulfonylhydrazones, msh 1–3, and their metal carbonyl complexes were characterized by elemental analysis, mass spectrometry, IR, and 1H and 13C–{1H} NMR spectroscopy. According to all the spectroscopic data, msh 1–3 are monodentate and coordinate via thiophene ring sulfur. The msh 1–3 must act as two-electron donors to satisfy the 18-electron rule. Graphical Abstract

Oligomeric Thiosemicarbazones as Novel Immobilization Matrix in Biosensing Applications

Thiosemicarbazone (TSC) matrices are constructed by electrochemically oligomerization on the graphite electrodes to investigate their matrix properties in terms of biomolecule immobilization for the biosensor applications. Amino functionalized oligomeric TSCs were successfully applied for the glucose oxidase (GOx) immobilization using glutaraldehyde (GA) as the crosslinker. Scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FT-IR) measurements are used to characterize the modified surface. Electrochemical measurements of the GOx biosensor were performed at ambient conditions at −0.7 vs. Ag/AgCl electrode by following the oxygen consumption resulting from the enzyme activity, in the presence of glucose substrate. Linearity, operational stabilities and repeatability are investigated in detail, as well as optimization of pH and enzyme amount,. The optimized biosensor shows a very good linearity between 0.05 mM and 1.0 mM glucose with a 10 s response time. Kinetic parameters such as Km and Imax are also calculated. Besides the batch configuration, the analytical characteristics of the system were also evaluated in flow injection analysis (FIA) mode. Finally, the new biosensor configuration was applied for glucose determination on a real sample.

Photochemical Reactions of M(CO) 5 THF (M = Cr, Mo, W) with Salen Type (-ONNO-) Schiff Bases

The hitherto unknown complexes, cis-[M(CO) 2 (η 4 -H 2 L′)], [M = Cr; 1, Mo; 2, W; 3] and cis-[M(CO) 2 (η 4 -H 2 L”)], [M = Cr; 4, Mo; 5, W; 6] have been synthesized by the photochemical reactions of photogenerated intermediate, M(CO) 5 THF (M = Cr, Mo, W) with salen type Schiff base ligands, N,N′-bis(salicylidene)-1,4-diaminobutane (H 2 L′) and N,N′-bis(2-hydroxy-3-methoxybenzylidene)ethylenediamine (H 2 L”). The complexes have been characterized by elemental analyses, LC- mass spectrometry, magnetic studies, FTIR and 1 H NMR spectroscopy. The spectroscopic studies show that H 2 L′ and H 2 L” ligands coordinated to the central metal as tetradentate ligands coordinating via the central azomethine nitrogens (C = N) and phenolic oxygen atoms in complexes 1-3 and via aromatic methoxy and phenolic oxygen atoms in complexes 4-6, respectively.