SINTEZA, STRUCTURA ŞI PROPRIETĂŢILE MAGNETICE ALE COMPUŞILOR COORDINATIVI AI FIERULUI CU DERIVAŢII REACTIVULUI GIRARD T

La condensarea reactivului Girard T cu aldehida 5-bromsalicilică se formează o hidrazonă nouă [H2(5BrSalGT)]Cl. Acest ligand tridentat este solubil în apă şi reacţionează cu ionii de fier cu formarea compusului coordinativ [FeLCl2], care interacţionează în soluţii apoase cu ionul azid N3- şi rezultă produşii [FeL(N3)2]2 (1) şi [Fe(L)2]N3.6H2O (2). Analiza cu raxe X pentru 1 şi 2 relatează că în procesul de coordinare ligandul se deprotonează şi se coordinează la metal în formă monoanionică. Proprietăţile magnetice ale compuşilor 1 şi 2 demonstrează un comportament paramagnetic funcţie de temperatură.SYNTHESIS, STRUCTURE AND MAGNETIC PROPERTIES OF IRON COORDINATION COMPOUNDS WITH GIRARD T REAGENTThe condensation of 5-bromosalicylaldehyde with Girard’s T reagent yields a new hydrazone [H2(5BrSalGT)]Cl. This tridentate ligand is soluble in water and react with iron ions with the formation of coordination compound [FeLCl2]. In water solutions [FeLCl2] interact with azide ion N3- allowing the formation of [FeL(N3)2]2 (1) and [Fe(L)2]N3.6H2O (2) compounds. The crystallographic studies of 1 and 2 show that in the coordination process the ligand is deprotonated and coordinate to the metal as monoanion. The cryomagnetic studies of 1 and 2 show a paramagnetic behaviour.</p

SINTEZA, STRUCTURA ŞI PROPRIETĂŢILE COMPUŞILOR COORDINATIVI AI FIERULUI CU 4-FENILTIOSEMICARBAZONA ŞI 4-FENIL-S-METILTIOSEMICARBAZONA 2-ACETILPIRIDINEI

În acest articol este realizată sinteza compuşilor Fe(III) cu 4-feniltiosemicarbazona şi 4-fenil-S-metiltiosemicar­bazo­na 2-acetilpiridinei, fiind propus studiul cristalografic şi magnetic al acestor compuşi cât şi studiul spectrofotometric în soluţie pentru ionii Fe(II) cu aceiaşi liganzi. Compuşii coordinativi [Fe(L1)2]BF4·CH3OH (1) şi [Fe(L2)2]FeCl4 (2) au fost obţinuţi în soluţii alcoolice. Analiza cu raze X relevă faptul că metilarea atomului de sulf influenţează asupra modului de coordinare a liganzilor la ionul de Fe(III). Compuşii 1 şi 2 mani­festă proprietăţi magnetice diferite.SYNTHESIS, STRUCTURE AND PROPERTIES OF IRON COORDINATION COMPOUNDS WITH 2-ACETYLPYRIDINE 4-PHENYLTHIOSEMICARBAZONE AND DERIVATIVESThe synthesis, crystallographic and magnetic studies of Fe(III) compounds with 4-phenylthiosemicarbazone and 4-phe­nylthiosemicarbazone 2-acetylpyridine are presented. The spectrophotometric studies in solution were realized for Fe(II) ions with the same ligands. The coordination compounds [Fe(L1)2]BF4·CH3OH (1) and [Fe(L2)2]FeCl4 (2) were obtained from alcoholic solutions. Crystallographic studies reveal that the methylation of sulfur atom influence the coordination set on the Fe(III) ion. Compounds 1 and 2 shows different magnetic properties in function of temperature.</p

SINTEZA ŞI STRUCTURA COMPUŞILOR COORDINATIVI AI CUPRULUI(II) CU TIOSEMICARBAZONA ALDEHIDEI 5-(METILENTRIMETILAMONIU)SALICILICE

A fost sintetizată clorura tiosemicarbazonei aldehidei 5-(metilentrimetilamoniu)salicilice în formă de sare ((H2L)Cl∙1.5H2O), iar la interacţiunea acesteia cu diferite săruri de cupru(II) în mediu neutru au fost obţinuţi patru compuşi cu formulele [Cu(HL)Cl]Cl∙2.25H2O (1), [Cu(HL)(Cl)(NO3)]∙2H2O (2), [Cu(H2L)Cl]SO4∙0.75H2O (3) şi [Cu(HL)Cl]ClO4∙1.75H2O (4), ce au fost stabilite cu ajutorul razelor X. Trei compuşi ai cuprului sunt compuşi ionici, formaţi din cationul complex [Cu(HL)Cl]+ ori [Cu(H­2L)Cl]2+, anionii fiind Cl-, ClO4- şi SO42- respectiv, iar compusul ce conţine anionul NO3- este un complex molecular. Toţi compuşii conţin molecule de apă de solvatare. Liganzii (HL)0/(H2L)+ în 1, 2, 4 / 3 coordinează tridentat prin setul de atomi donori O,N,S în formă de ion bipolar, singur fiind electroneutru, însă conţinând două centre ionice (Zwitter-ion) ori în forma sa protonată, respectiv. Raportul molar de combinare Cu:(HL)0/(H2L)+ în aceşti compuşi este 1:1. În rezultatul coordinării liganzii organici (HL)0/(H2L)+ suferă schimbări conformaţionale, iar primii sunt supuşi monodeprotonării.SYNTHESIS AND STRUCTURE OF COORDINATION COMPOUNDS OF COPPER(II) WITH 5-(METHYLENETRIMETYLAMONIUM)SALICYLALDEHYDE THIOSEMICARBAZONE 5-(methylenetrimetylamonium)salicylaldehyde thiosemicarbazone in salt form ((H2L)Cl∙1.5H2O)  was synthesized, at the interaction of this with various salts of copper(II) in neutral media were obtained four compounds with the formula: [Cu(HL)Cl]Cl∙2.25H2O (1), [Cu(HL)(Cl)(NO3)]∙2H2O (2), [Cu(H2L)Cl]SO4∙0.75H2O (3) and [Cu(HL)Cl]2ClO4∙1.75H2O (4), investigated by single crystal X-ray diffraction. It was established that four copper compounds has an ionic form, com­posed from cationic complex [Cu(HL)Cl]+ and [Cu(H­2L)Cl]2+, anions Cl-, ClO4- and SO42- respectively, for compond with NO3- anion the complex is molecular. All compounds contain water molecules of salvation. The ligand (HL)0/(H2L)+  in 1, 2, 3 / 4 is tridentate coordinated via set of donor atoms O, N, S with the geometry of bipolar ion, where the ligand is electroneutral but contains two ionic centres (Zwitterion) or in its protonated form respectively. The molar ratio of the combination Cu:(HL)0/(H2L)+ in these compounds is 1:1. As a result of coordination of organic ligand (HL)0/(H2L)+ is not only subjected of monodeprotona­tion, but also supports conformational changes.</p

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments

SINTEZA, STRUCTURA ȘI PROPRIETĂȚILE COMPUȘILOR COORDINATIVI AI CUPRULUI(II) CU DERIVAȚII TIOSEMICARBAZONEI 8-FORMILCHINOLINEI

În acest studiu este descrisă sinteza și analiza cristalografică a compusului coordinativ al cuprului(II) cu tiosemicar­bazona 8-formilchinolinei. În soluţii diluate la temperatura camerei, reactivii organici reacţionează cu ionii de cupru(II) formând compuşi de culoare galbenă, cu raportul de combinare metal:ligand = 1:1. Compusul coordinativ al cuprului(II) cu 4-feniltiosemicarbazona 8-formilchinolinei este caracterizat spectral printr-un maxim de absorbție localizat la at λ =390 nm. Curba de calibrare are un caracter liniar în domeniul de concentraţii ale cuprului 2,5∙10-6 ÷ 4∙10-5 M. 4-fenil­tiosemicarbazona 8-formilchinolinei a fost propusă în calitate de reactiv pentru determinarea spectrofotometrică a cuprului. Metoda de determinare cantitativă a cuprului este binevenită în cazul când randamentul reacţiilor de formare a compu­şilor coordinativi cu liganzi organici este mic. Compusul [CuLAc] manifestă activitate antibacteriană față de bacteriile Staphylococcus aureus (tulpina 209-P), Entrecoccus faecalis și Proteus vulgaris.SYNTHESIS, STRUCTURE AND PROPERTIES OF COPPER(II) COORDINATION COMPOUNDS WITH 8-FORMILQUINOLINE THIOSEMICARBAZONE DERIVATIVES In this study we show the synthesis and crystallographic investigation of Cu(II) coordination compounds with 8-formyl­quinoline thiosemicarbazone. In dilute solutions the copper ions react with organic reagents at room temperature to form 1:1 = metal:ligand yellow coloured complexes. Complex of copper(II) with 8-formylquinoline 4-phenyl­thiosemi­car­bazone in aqueous ethanol solution is characterized by a maximum absorption located at λ=390 nm. The calibration curve has a linear character in the range of copper concentrations 2.5∙10-6 ÷ 4∙10-5 M. The 8-formylquinoline 4-phenyl­thiosemicarbazonev is proposed for the spectrophotometric determination of copper(II) ions in solution. The method has been successfully applied for the determination of copper when the yield of coordination reactions with organic ligands is small. Compound [CuLAc] exhibiting antibacterial activity against Staphylococcus aureus (strain 209-P), Entrecoccus faecalis and Proteus vulgaris bacteria.</p

New template reactions of salicylaldehyde S-methyl-isothiosemicarbazone with 2-formylpyridine promoted by Ni(II) or Cu(II) metal ions

The template reaction between salicylaldehyde S-methyl-isothiosemicarbazone and 2-formylpyridine in presence of nickel(II) or copper(II) salts yields two new coordination compounds with general formula [NiL1]2 (1) and [CuL2]2 (2) (L1 = the dianionic (N1-salicylidene)(N4-(hydroxy(pyridin-2-yl)methyl) Smethyl- isothiosemicarbazide) ligand and L2 = the doubly deprotonated (N1-salicylidene)(N4-(picolinoyl) S-methyl-isothiosemicarbazide) ligand). In the complex 1, the formed L1 ligand appears as result of an addition reaction of the precursors, while for 2 a redox mechanism is implicated in the formation of L2. Despite the fact that the initial organic precursors are the same, the resulting ligands obtained in the template reaction are different. In 1, the Ni(II) metal ion adopts a square-planar geometry and the [NiL1] units are forming dimerized chains through weak Ni...Ni interactions (3.336 and 3.632 Å). In 2, the Cu(II) metal ions adopt a square-pyramidal geometry and form dinuclear species through weak Cu...O (phenoxo) interactions. The magnetic susceptibility measurements of the complexes reveal the diamagnetic nature of 1 as expected for a square planar Ni(II) complex and a paramagnetic behavior for 2 with weak intra-dimer antiferromagnetic interaction (J/kB = -2.1(1) K). 2011 Elsevier B.V. All rights reserved

Synthesis, crystal structure and characterizations of iron(III) and copper(II) complexes with the hydrazone ligand obtained from 2-formyl-pyridine and Girard's T reagent

The condensation of 2-formyl-pyridine with Girard's T reagent yields a new hydrazone in the form of an ammonium quaternary salt: [H(2-PyGT)]Cl. This tridentate ligand is readily soluble in water and reacts with iron(III) or copper(II) chlorides to give [Fe(2-PyGT)Cl3] (1) or [Cu(2-PyGT)Cl2]-(H2O) (2) complexes, respectively. Single-crystal X-ray studies in 1 and 2 reveal that the coordination reaction gives rise to the deprotonation of the organic ligand that is coordinated using its NNO donor atoms in the form of a zwitterion species. The coordination spheres around the transition metal ions in complexes 1 and 2 are quite different. In 1, the iron site adopts a distorted octahedral coordination sphere, while the Cu(II) ions in 2 show a distorted tetragonal-pyramid geometry. As expected, the magnetic properties of these compounds reveal only weak antiferromagnetic interaction between spin carriers

Bilayer Thin Films That Combine Luminescent and Spin Crossover Properties for an Efficient and Reversible Fluorescence Switching

International audienceWe report on the vacuum thermal deposition of bilayer thin films of the luminescent complex Ir(ppy)3, tris[2-phenylpyridinato-C2,N]iridium(III), and the spin crossover complex [Fe(HB(tz)3)2], bis[hydrotris(1,2,4-triazol-1-yl)borate]iron(II). Switching the spin state of iron ions from the low spin to the high spin state around 337 K leads to a reversible jump of the luminescence intensity, while the spectrum shape and the luminescence lifetime remain unchanged. The luminescence modulation occurs due to the different UV light absorption properties of the iron complex in the two spin states and its magnitude can therefore be precisely adjusted by varying the film thickness. These multilayer luminescence switches hold potential for micro- and nanoscale thermal sensing and imaging applications