- Metallo-hydrazone complexes immobilized in zeolite Y: Synthesis, identification and acid violet-1 degradation
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Copper(II), cobalt(II) and nickel(II) complexes of hydrazone ligand (SAPH) derived from salicylaldehyde and phenylhydrazine have been encapsulated in zeolite-Y super cages via ship-in-a-bottle synthesis. Detailed characterization of the intrazeolitic complexes were performed by elemental analysis, spectral (FT-IR, UV-Vis.) studies, magnetic measurements and X-ray diffraction. Furthers, surface texture and thermal analysis (TG, DTG, DTA) have provided further evidence for successful immobilization of the metal complexes inside zeolite Y. Investigation of the stereochemistry of these incorporated chelates pointed out that, SAPH ligand is capable to coordinate with the central metal through the (CN), phenolic (OH) and (NH) groups forming polynuclear structures. The involvement of zeolite oxygen in coordination was postulated in the hybrid materials. The intrazeolitic copper, cobalt and nickel-SAPH complexes have distorted tetrahedral, octahedral and square-pyramidal configurations, respectively. The zeolite encapsulated complexes are thermally stable up to 800 °C except Cu(II) sample which is thermally stable up to midpoint 428 °C. The assessment of the catalytic activity was performed by the use of the photo-degradation of acid violet-1 dye as a probe reaction in presence of H 2O2 as an oxidant. Decolorization of acid violet-1 dye was examined under the same conditions whereas the unpromoted zeolite and Cu II, CoII, NiII-hydrazone complexes supported on zeolite showed 13% and 76%, 53%, 43% color removal, respectively. The results revealed that, the zeolite encapsulated Cu(II) complex generally exhibited better catalytic efficiency (76%) compared with other investigated zeolite encapsulated metal-hydrazone samples.
- Ahmed, Ayman H.,Thabet
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Read Online
- Salicylaldehyde phenylhydrazone: A new highly selective fluorescent lead (II) probe
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The fluorescence intensity of salicylaldehyde phenylhydrazone (L), in 1:1 (v/v) CH3OH:H2O was enhanced by ca. 100 times with a blue shift in emission maximum, on interaction with Pb2+ ion. No enhancement in fluorescent intensity of L was observed on interaction with metal ions - Na+, K+, Ca2+, Cu2+, Ni 2+, Zn2+, Cd2+ and Hg2+. This signal transduction was found to occur via photoinduced electron transfer (PET) mechanism. A 1:1 complexation between Pb2+ and L with log β = 7.86 has been proved from fluorescent and UV/Visible spectroscopic data. The detection limit of Pb2+ was calculated to be 6.3 × 10 -7 M.
- Das, Diganta Kumar,Goswami, Priyanka,Sarma, Smita
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Read Online
- METHODS OF FORMING IMINES, IMINE-RELATED AND IMINE-DERIVED COMPOUNDS USING GREEN SOLVENTS
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The present disclosure relates to using green solvents to synthesize an array of imines, imine-related and imine-derived compounds in an efficient and eco-friendly matter, satisfying green chemistry requirements. Reaction embodiments are performed using solvents, such as ethyl lactate and dimethyl isosorbide, which are both individually characterized as green. In embodiments, solvents include lactic whey and/or water as co-solvents. In these green solvents, the synthesis process discussed herein can produce up to quantitative yields of product at room temperature in a short duration. Embodiments include a method of forming an imine, imine-related or imine-derived compound product. In embodiments, the methods include mixing an aldehyde reactant with a nucleophilic/nitrogen-containing reactant in a green solvent at a temperature between negative twenty degrees Celsius (?20° C.) and positive fifty degrees Celsius (50° C.); stirring the mixture; and forming an imine, imine-related or imine-derived compound product.
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Paragraph 0184-0185
(2021/10/22)
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- Synthesis and characterization of hydrazone and azine derivatives of bis(cyclopentadienyI) titanium(IV)
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Pentacoordinated hydrazone and azine derivatives of bis(cyclopentadienyl)titanium(IV) of the type {equation presented}, have been prepared. The products were characterized by chemical analyses, elec- trical conductance, IR, 1H NMR, and electronic spectral studies. Some hydrazone complexes and a few azine com- plexes of titanium have been studied.' ' However, no systematic study on their organometallic derivatives is available. In view of the versatile chelating ability, widespread applications and lack of data involving organometallic derivatives of titanium, it has been considered of interest to study the reactions of Cp2TiCl2 with the title ligands.
- Kaushik, Narender Kumar,Khera, Brij,Sharma, Anand Kumar
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p. 793 - 794
(2021/11/22)
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- Diazaborines Are a Versatile Platform to Develop ROS-Responsive Antibody Drug Conjugates**
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Antibody–drug conjugates (ADCs) are a new class of therapeutics that combine the lethality of potent cytotoxic drugs with the targeting ability of antibodies to selectively deliver drugs to cancer cells. In this study we show for the first time the synthesis of a reactive-oxygen-species (ROS)-responsive ADC (VL-DAB31-SN-38) that is highly selective and cytotoxic to B-cell lymphoma (CLBL-1 cell line, IC50 value of 54.1 nM). The synthesis of this ADC was possible due to the discovery that diazaborines (DABs) are a very effective ROS-responsive unit that are also very stable in buffer and in plasma. DFT calculations performed on this system revealed a favorable energetic profile (ΔGR=?74.3 kcal mol?1) similar to the oxidation mechanism of aromatic boronic acids. DABs’ very fast formation rate and modularity enabled the construction of different ROS-responsive linkers featuring self-immolative modules, bioorthogonal functions, and bioconjugation handles. These structures were used in the site-selective functionalization of a VL antibody domain and in the construction of the homogeneous ADC.
- Aguiar, Sandra I.,André, Ana S.,António, Jo?o P. M.,Bernardes, Gon?alo J. L.,Carvalho, Joana Inês,Dias, Joana N. R.,Faustino, Hélio,Gois, Pedro M. P.,Lopes, Ricardo M. R. M.,Veiros, Luis F.,da Silva, Frederico A.
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p. 25914 - 25921
(2021/11/09)
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- Shaken, not stirred: a schools test for aldehydes and ketones
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A schools test for aldehydes and ketones in water at room temperature using test tubes has been developed in this laboratory using either phenylhydrazine hydrochloride or phenylhydrazine hydrochloride with NaOAc . 3H2O. The role of one equivalent of a strong or weak acid which catalyses the reaction is discussed.
- Plater, M John
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p. 104 - 107
(2019/11/22)
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- Zeolite enslaved transition metal complexes as novel heterogeneous catalysts for synthesis of polycyclic heterocycles using suzuki–miyaura cross coupling reaction under greener conditions
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In the present work we report the construction of zeolite enslaved transition metal complexes (Pd2+, Ni2 + ) as novel heterogenous catalysts for synthesis of polycyclic heterocycles using suzuki–miyaura cross coupling reaction in ethanolic medium. The synthesized catalysts were characterized by employing UV–Vis, FT-IR, magnetic susceptibility, N2 sorption, XRD, XPS, FE-SEM analysis. Results of the study advocate that newly developed catalysts give rise to a rapid and easy synthesis of various polycyclic heterocycles by Suzuki coupling reactions in impressive yields. In conclusion, developed catalyst may be used as versatile tool in the synthesis of various industrially and pharmaceutically important polycyclic heterocycles under greener conditions.
- Dwivedi, Jaya,Jain, Sonika,Kishore, Dharam,Mishra, Shruti,Sain, Shalu,Sankararamakrishnan, Nalini,Sharma, Swapnil,Sharma, Vivek,Srivastava, Manish,Wabaidur, Saikh M
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- Lewis acid–catalyzed green synthesis and biological studies of pyrrolo[3,4-c]pyrazoles in aqueous medium
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An environmentally benign approach in aqueous medium by means of Lewis acid catalyst affords a wide spectrum of pyrazoline derivatives in satisfactory yields. [3+2] cycloaddition reactions of substituted azomethine-N-imines to maleimide in aqueous medium at relatively high concentrations of Lewis acid catalyst have emerged as an environment friendly alternative to conventional solvents. Promising catalytic activity has been revealed by Lewis acid like Cu (NO3)2 in aqueous medium. The obvious features of this synthetic protocol were short reaction time, high efficiency, less hazardous synthesis by benign solvent, catalysis, modest workup, and a clean reaction methodology.
- Arjuna, Anania,Kaur, Manpreet,Singh, Baldev
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- Synthesis of novel 3-phenyl-2-oxido/sulfido-1,3,4,2-benzoxadiazaphosphepines
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An efficient and facile synthetic approach towards a series of novel 3-phenyl-2-oxido/sulfido-2,3-dihydro-1,3,4,2-benzoxadiazaphosphepines 2–7 was described. The method depended on the cyclocondensation of equimolar ratios of salicylaldehyde phenylhydrazone (1) with different examples of phosphorus halides and phosphorus sulfides in toluene containing triethylamine as a catalyst. In the same manner, the fusion of salicylaldehyde phenylhydrazone (1) with triethyl phosphate in the presence of DBU afforded the 2-ethoxy-1,3,4,2-benzoxa-diazaphosphepine 8, while a fusion of compound 1 with diethyl phosphite and tris(2-chloroethyl)phosphite led to the formation of new examples of 1,2-benzoxaphospholes 9 and 10, respectively. Interestingly, the reaction of compound 1 with diethyl ethoxycarbonyl phosphonate in ethanol containing DBU as a catalyst furnished the chromeno[3,4-d][1,2,3]diazaphosphole derivative 12 as a regioselective product.
- Ali, Tarik E.,Assiri, Mohammed A.,Yahia
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p. 1828 - 1837
(2018/06/25)
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- Facile synthesis of pyrazoles by iron-catalyzed regioselective cyclization of hydrazone and 1,2-diol under ligand-free conditions
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A facile synthesis of pyrazoles by the cyclization of hydrazones and 1,2-diols was described. In the presence of ferric nitrate, the reaction occurs under neat conditions and makes the use of potassium persulfate to oxidize the diol to α-hydroxy carbaldehyde for the reaction with hydrazones to produce 1,3- and 1,3,5-substituted pyrazoles selectively. The overall regioselective transformation occurs in one-pot under ligand-free, mild conditions even in the presence of air.
- Panda, Niranjan,Ojha, Subhadra
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p. 244 - 251
(2018/03/13)
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- Organocatalytic synthesis of densely functionalized oxa-bridged 2,6-epoxybenzo[: B] [1,5]oxazocine heterocycles
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Metal-free addition of salicylhydrazones to electron deficient internal alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles was achieved. The demonstrated protocol proceeds through an o-quinone methide formation, aza-Michael addition, stereoselective protonation, enamine promoted aromatization, O,O-acetalization and O,N-aminalization sequence to provide privileged heterocycles in good yields with high diastereoselectivities.
- Gurubrahamam, Ramani,Nagaraju, Koppanathi,Chen, Kwunmin
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supporting information
p. 6048 - 6051
(2018/06/18)
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- Fluorimetric detection of Sn2?+ ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis
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The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3?nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn2?+ ions by enhancing the fluorescence intensity preference to Cu2?+, Fe3?+, Fe2?+, Ni2?+, NH4+, Ca2?+, Pb2?+, Hg2?+ and Zn2?+ ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV–visible and fluorescence titration with and without Sn2?+ helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn2?+ and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn2?+ is further used to develop an analytical method for detection of Sn2?+ from aqueous medium in environmental samples.
- Patil, Kishor S.,Mahajan, Prasad G.,Patil, Shivajirao R.
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p. 131 - 137
(2016/07/20)
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- Kinetic Selectivity and Thermodynamic Features of Competitive Imine Formation in Dynamic Covalent Chemistry
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The kinetic and thermodynamic selectivities of imine formation have been investigated for several dynamic covalent libraries of aldehydes and amines. Two systems were examined, involving the reaction of different types of primary amino groups (aliphatic amines, alkoxy-amines, hydrazides and hydrazines) with two types of aldehydes, sulfobenzaldehyde and pyridoxal phosphate in aqueous solution at different pD (5.0, 8.5, 11.4) on one hand, 2-pyridinecarboxaldehyde and salicylaldehyde in organic solvents on the other hand. The reactions were performed separately for given amine/aldehyde pairs as well as in competitive conditions between an aldehyde and a mixture of amines. In the latter case, the time evolution of the dynamic covalent libraries generated was followed, taking into consideration the operation of both kinetic and thermodynamic selectivities. The results showed that, in aqueous solution, the imine of the aliphatic amine was not stable, but oxime and hydrazone formed well in a pH dependent way. On the other hand, in organic solvents, the kinetic product was the imine derived from an aliphatic amine and the thermodynamic products were oxime and hydrazone. The insights gained from these experiments provide a basis for the implementation of imine formation in selective derivatization of mono-amines in mixtures as well as of polyfunctional compounds presenting different types of amino groups. They may in principle be extended to other dynamic covalent chemistry systems.
- Kulchat, Sirinan,Chaur, Manuel N.,Lehn, Jean-Marie
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supporting information
p. 11108 - 11118
(2017/08/22)
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- La(OTf)3 catalyzed reaction of salicylaldehyde phenylhydrazones with β-ketoesters and activated alkynes: Facile approach for the preparation of chromenopyrazolones
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A facile approach has been developed for the preparation of chromenopyrazolones (5a-o, 7a-k) by the reaction of salicylaldehyde phenylhydrazones (3a-o) with β-ketoesters (4a, 4f-g) and activated alkynes (6a-e) in the presence of La(OTf)3 with good yields. However, the reaction of salicylaldehyde phenylhydrazones (3a, 3c, 3j-k, 3n) with ethyl 4-chloro-3-oxobutanoate (4e) underwent cyclization with reductive dechlorination and provided the methyl chromenopyrazolones instead of chloromethyl chromenopyrazolones. The present solvent free protocol provided the novel heterocyclic compounds.
- Hariprasad, Kurma Siva,Prasad, Kasagani Veera,Raju, Bhimapaka China
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p. 108654 - 108661
(2016/11/30)
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- Intramolecular Catalysis of Hydrazone Formation of Aryl-Aldehydes via ortho -Phosphate Proton Exchange
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Bioorthogonal site-specific chemical reaction to label biomolecules in vitro and in living cells is one of the most powerful and convenient tools in chemical biology. Reactive pairs frequently used for chemical conjugation are aldehydes/ketones with hydrazines/hydrazides/hydroxylamines. Although the reaction is generally specific for the two components, even in a cellular environment, the reaction is very slow under physiological conditions. Addition of a phosphate group at the ortho position of an aromatic aldehyde increases the reaction rate by an order of magnitude and enhances the aqueous solubility of the reagent and the product. We have synthesized phosphate-substituted aldehyde synthetic models to study kinetics of their reactions with hydrazines and hydrazides that contain a fluorophore. This rapid bioorthogonal reaction should therefore be potentially a very useful reaction for routine site-specific chemical ligations to study and image complex cellular processes in biological systems.
- Dilek, Ozlem,Sorrentino, Anthony M.,Bane, Susan
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p. 1335 - 1338
(2016/06/01)
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- Orthometallation in bidentate Schiff base ligands via C-H activation: Synthesis of ruthenium(III) organometallic complexes
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Schiff bases obtained by the reactions of substituted aromatic aldehydes with phenyl hydrazine or 2,4-dinitrophenyl hydrazine were synthesized and characterized by spectroscopic methods. Cyclometalated Ru(III) complexes of general formula, namely [Ru(L)(PPh3)2Cl], were synthesized from the Schiff bases via C-H bond activation and characterized by spectroscopic and electrochemical studies. In addition, one molecular structure of one of the complexes was determined by X-ray crystallography. The redox behavior of the complexes was examined by electrochemical studies, and one mechanism of orthometallation was investigated.
- Ghosh, Kaushik,Kumar, Rajan,Kumar, Sushil,Bala, Manju,Singh, Udai P.
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p. 831 - 837
(2015/10/28)
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- Synthesis of novel triazoles, tetrazine, thiadiazoles and their biological activities
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An expedient synthesis of novel triazoles, tetrazine and thiadiazoles, using conveniently accessible and commercially available starting materials has been achieved. The synthesized compounds were characterized by spectroscopic and elemental analyses, and screened for their antibacterial activities against four different strains, namely E. coli, P. aeruginosa, S. aureus and B. megaterium. In particular, the compounds 5, 24 and 26h exhibited excellent antibacterial activities compared to the reference antibiotic. To get further insight about their behavior, these compounds were tested for their antioxidant activities via SOD-like activity, DPPH free radical scavenging activity, ABST and NO, which showed promising results. Furthermore, these compounds effectively promoted the cleavage of genomic DNA as well, in the absence of any external additives.
- Al-Omair, Mohammed A.,Sayed, Abdelwahed R.,Youssef, Magdy M.
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p. 2591 - 2610
(2015/03/04)
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- In situ room temperature synthesis and characterization of salicylaldehyde phenylhydrazone metal complexes, their cytotoxic activity on MCF-7 cell line, and their investigation as antibacterial and antifungal agents
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In situ synthesis is usually used in industrial plants. As an approach new series of metal complexes of the salicylaldehyde phenylhydrazone, H2L, have been synthesized and characterized by elemental analysis, IR, UV, 1H-NMR, 13
- El-Seidy, Ahmed M. A.
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p. 437 - 446
(2014/12/11)
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- Synthesis and antifungal activity of substituted salicylaldehyde hydrazones, hydrazides and sulfohydrazides
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Efficient synthetic procedures for the preparation of acid hydrazines and hydrazides were developed by converting the corresponding carboxylic acid into the methyl ester catalyzed by Amberlyst-15, followed by a reaction with hydrazine monohydrate. Sulfohydrazides were prepared from the corresponding sulfonyl chlorides and hydrazine monohydrate. Both of these group of compounds were condensed with substituted salicylaldehydes using gradient concentration methods that generated a large library of hydrazone, hydrazide and sulfohydrazide analogs. Antifungal activity of the prepared analogs showed that salicylaldehyde hydrazones and hydrazides are potent inhibitors of fungal growth with little to no mammalian cell toxicity, making these analogs promising new targets for future therapeutic development.
- Backes, Gregory L.,Neumann, Donna M.,Jursic, Branko S.
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p. 4629 - 4636
(2014/11/08)
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- Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones
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In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.
- Akhbar, Ahmed R.,Chudasama, Vijay,Fitzmaurice, Richard J.,Powell, Lyn,Caddick, Stephen
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supporting information
p. 743 - 746
(2014/01/06)
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- One-pot tandem synthesis of tetrasubstituted pyrazoles via 1,3-dipolar cycloaddition between aryl hydrazones and ethyl but-2-ynoate
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1,3,4,5-Tetrasubstituted pyrazoles are rapidly and regioselectively synthesized in a one-pot, three-step sequence consisting of condensation, nitrilimine generation, and cycloaddition using mercuric acetate. Newly synthesized compounds were characterized by spectral studies. Regiochemistry of compounds 6a and 8a was determined as 1,4- and 1,5-regioisomers respectively by X-ray crystallography. Copyright
- Ningaiah, Srikantamurthy,Doddaramappa, Shridevi D.,Chandra,Madegowda, Mahendra,Keshavamurthy, Shubakara,Bhadraiah, Umesha K.
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supporting information
p. 2222 - 2231
(2014/07/07)
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- The enhanced efficiency to 3.6% based on organic dye as donor and Si/TiO2 acceptor bulk hetero-junction solar cells
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The efficient organic dyes 2-{4-[2-(2-hydroxybenzylidene)hydrazino]phenyl} ethylene-1,1,2-tricarbonitrile and 2-{4-[2-(4-hydroxybenzylidene)hydrazino] phenyl}ethylene-1,1,2-tricarbonitrile have been synthesized, characterized and fabricated as hetero-junction solar cell materials. We use B3LYP/6-31G*, B3LYP/6-31G** and HF/6-31G** level of theories to optimize the ground state geometries. The absorption wavelengths have been computed by using time dependent density functional theory which is in good agreement with the experimental data. The hetero-junction solar cell devices have been fabricated by organic-inorganic heterojunction (dye/Si/TiO 2) and measured the efficiency by applying the incident power 30, 50 and 70 mW/cm2. The maximum efficiency 3.6% for dye2 has been observed. We shed light on the electronic and charge transport properties. Moreover, the stability and external quantum efficiencies have been measured.
- Al-Sehemi, Abdullah G.,Irfan, Ahmad,Al-Melfi, Mohrah Abdullah M.,Al-Ghamdi, Ahmed A.,Shalaan
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- Fast hydrazone reactants: Electronic and acid/base effects strongly influence rate at biological pH
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Kinetics studies with structurally varied aldehydes and ketones in aqueous buffer at pH 7.4 reveal that carbonyl compounds with neighboring acid/base groups form hydrazones at accelerated rates. Similarly, tests of a hydrazine with a neighboring carboxylic acid group show that it also reacts at an accelerated rate. Rate constants for the fastest carbonyl/hydrazine combinations are 2-20 M-1 s-1, which is faster than recent strain-promoted cycloaddition reactions.
- Kool, Eric T.,Park, Do-Hyoung,Crisalli, Pete
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supporting information
p. 17663 - 17666
(2014/01/06)
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- Enhancers of protein degradation
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The present invention relates to compounds suitable for modulating huntingtin protein processing and useful for treating or preventing huntingtin-related disorders. The invention provides pharmaceutical compositions comprising said compounds and methods of syntheses thereof.
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Page/Page column 14
(2011/04/14)
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- ENHANCERS OF PROTEIN DEGRADATION
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The present invention relates to compounds suitable for modulating huntingtin protein processing and useful for treating or preventing huntingtin-related disorders. The invention provides pharmaceutical compositions comprising said compounds and methods of syntheses thereof.
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Page/Page column 25-26; 36
(2011/04/13)
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- A convenient approach to the synthesis of different types of schiff's bases and their metal complexes
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Various metal complexes derived from different Schiff bases are conveniently prepared using solvent-free condensation reactions in one-pot synthesis, resulting in significantly enhanced yields. Initial calorimetric studies, and/or TGA of reaction mixtures, led to better optimization of reaction conditions. The ligands like imines, hydrazones, semicarbazones, and nitrones are also synthesized by this method; thus this process is general and expedient.
- Pradhan, Kiran,Selvaraj, Kaliaperumal,Nanda, Ashis K.
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supporting information; experimental part
p. 1078 - 1079
(2011/01/09)
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- Dowex polymer-mediated protection of carbonyl groups
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Dowex (strongly acidic cationic exchange resin) polymer is employed as solid acid catalyst for the clean and less hazardous protection of carbonyl compounds as phenylhydrazones and 2,4-dintrophenylhydrazones in ethanol under reflux conditions. The reactions proceed very smoothly and the yields of the derivatives are excellent. Copyright Taylor & Francis, Inc.
- Niknam, Khodabakhsh,Kiasat, Ali Reza,Karimi, Sadegh
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p. 2231 - 2236
(2007/10/03)
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- Hydrazone, hydrazine and thiosemicarbazone derivatives as antifungal agents
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Disclosed are pharmaceutical compositions comprising aryl and heteroaryl hydrazone, hydrazine and thiosemicarbazone derivatives of formulae I and II, and methods for using the compositions as antifungal agents. The invention also relates to novel aryl and heteroaryl hydrazone, hydrazine and thiosemicarbazone derivatives of formulae I and II, their preparation, to pharmaceutical compositions containing them, and to methods of using them to alleviate fungal infections.
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- Ruthenium-(II)/-(III) terpyridine complexes incorporating imine functionalities. Synthesis, structure, spectroscopic and electrochemical properties
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A new class of ruthenium terpyridine complexes of the type [RuII(trpy)(L1-6)Cl] 1-6 (trpy=2,2':6',2''-terpyridine; L1-3=o--OC6H3(R)C(R')=NCH2C6H5 and L4-6=o--OC6H3(R)CH(R')N=NC6H5; where R=H or p-NO2 and R'=H or CH3) have been synthesized. The "free" ligands incorporating a NH spacer o--OC6H3(R)C(R')=NNHC6H5 (HL4-6) have undergone imine to azo tautomerism on co-ordination to the ruthenium terpyridine moiety in the complexes 4-6, whereas those having a CH2 spacer (HL1-3) remain unaltered on co-ordination. The diamagnetic, neutral complexes 1-6 exhibit strong MLCT transitions in the visible region and intraligand transitions in the UV region. A significant shift in MLCT band energy has been observed depending on the ligand field strength of the co-ordinated L. The complexes display a reversible ruthenium(III)-ruthenium (II) couple in the potential range of 0.12-0.63 V and a quasi-reversible ruthenium(IV)-ruthenium(III) couple in the range of 1.21-1.85 V versus SCE. The higher ligand field strength of the co-ordinated L4-6 compared to the co-ordinated L3- is reflected in the observed metal redox processes. The reduction of the co-ordinated terpyridine has been observed near -1.3 V. The complexes exhibit moderately strong emissions from the lowest energy MLCT bands in the range 661-690 nm in EtOH-MeOH (4:1 v/v) at 77 K. The quantum yields of the complexes (Φ=0.006-0.09) are found to be reasonably sensitive to the nature of the co-ordinated L. The oxidised complexes 3+ and 6+ have been isolated in the solid state as their perchlorate salts. The crystal structure of 3+ exhibits pseudo-octahedral trans geometry with regard to the relative disposition of the imine nitrogen (N4) of L3 and the central pyridyl group of the trpy ligand. The one-electron paramagnetic complexes show 1:1 conductivity and display ligand-to-metal charge transfer bands near 600 and 400 nm and intraligand transitions in the UV region. The observed rhombic EPR spectra at 77 K corresponding to the distorted octahedral geometry have been analysed to furnish values of axial (Δ) and rhombic (V) distortion parameters as well as the energies of the two expected ligand field transitions (ν1 and ν2) within the t2 shell.
- Mondal, Biplab,Chakraborty, Soma,Munshi, Pradip,Walawalkar, Mrinalini G.,Lahiri, Goutam Kumar
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p. 2327 - 2336
(2007/10/03)
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- General acid catalysis of boric acid and water on dehydration step in formation of phenylhydrazone from salicylaldehyde
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Hydrazone formation from salicylaldehyde and phenylhydrazine has been studied in water-ethanol (60:40 volume) solution at 35°C and ionic strength of 0.25 (with KCl). The reaction exhibits specific acid (in Ph4 dehydration of intermediate is rate determining step. Apparent catalytic rate constants of water and boric acid in the reaction are in good agreement with predicted values from Bronsted relationship. The kinetic results, UV, IR and NMR spectroscopic analyses exhibit general acid catalysis by boric acid and water.
- Mostaghim,Habibi Yangjeh,Gholami
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p. 976 - 978
(2007/10/03)
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- Synthesis and Characterization of Hydrazone and Azine Derivatives of Bis(cyclopentadienyl)titanium(IV)
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Pentacoordinated hydrazone and azine derivatives of bis(cyclopentadienyl)titanium(IV) of the type and , where R=H or CH3, R'=H, C6H5 or C6H3(NO2)2 and R''=H or CH3 have been prepared.The products were characterized by chemical analyses, electrical conductance, IR, 1H NMR, and electronic spectral studies.
- Khera, Brij,Sharma, Anand Kumar,Kaushik, Narender Kumar
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p. 793 - 794
(2007/10/02)
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- Synthesis and characterization of hydrazone and azine derivatives of bis(cyclopentadienyl)zirconium(IV)
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Pentacoordinated hydrazone and azine derivatives of bis(cyclopentadienyl)zirconium(IV) of the type and , where R = H or CH3 and R' = H, C6H5 or C6H3(NO2)2, have been synthesized by the reaction of bis(cyclopentadienyl)zirconium(IV) dichloride with the appropriate hydrazone or azine in equimolar ratios in refluxing tetrahydrofuran.The products were characterized by chemical analyses, electrical conductance, IR, 1H NMR and electronic spectral studies.
- Khera, B.,Sharma, A. K.,Kaushik, N. K.
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p. 172 - 174
(2007/10/02)
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- Complexes of Hydrazines with Crown Ethers and their Reaction with Carbonyl Compounds
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The stable crystalline stoichiometric complexes 3-8 of mono- and di-substituted hydrazines with crown ether-type neutral ligands (1, 2), described for the first time, are utilized for the synthesis of the corresponding substituted hydrazones in lipophilic solvents by the reaction with carbonyl compounds under phase transfer conditions.
- Voegtle, Fritz,Mueller, Walter M.
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p. 2081 - 2085
(2007/10/02)
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