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61.
Jadhav VD Herdtweck E Schmidtchen FP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(20):6098-6107
The bicyclic hexahydropyrimidino[1,2a]pyrimidine cationic scaffold has a well-known capacity to bind a variety of oxoanions (phosphates, carboxylates, squarates, phosphinates). Based on this feature, the parent host was supplemented with sec-carboxamido substituents to generate compounds 1-3 in an effort to improve the anion-binding affinity and selectivity and to learn about the role and magnitude of entropic factors. Bicyclic guanidinium compounds were prepared by a convergent strategy via the corresponding tetraester 22 followed by catalytic amidation. Host-guest binding studies with isothermal titration calorimetry in acetonitrile probed the behavior of artificial hosts 1-3 in comparison with the tetraallylguanidinium compound 4 on binding p-nitrobenzoate, dihydrogenphosphate, and 2,2'-bisphenolcyclophosphate guests that showed enhanced affinities in the 10(5)-10(6) M(-1) range. Contrary to expectation, better binding emerges from more positive association entropies rather than from stronger enthalpic interactions (hydrogen bonding). In an NMR spectroscopy titration in DMSO, o-phthalate was sufficiently basic to abstract a proton from the guanidinium function, as confirmed by an X-ray crystal structure of the product. The novel carboxamide-appended anchor groups also bind carboxylates and phosphates, but not hydrogen sulfate in methanol with affinities in excess of 10(4) M(-1). The energetic signature of the complexation in methanol is inverted with respect to acetonitrile solvent and shows a pattern of general ion pairing with strong positive entropies overcompensating endothermic binding enthalpies. This study provides an example of the fact that bona fide decoration of a parent guanidinium anchor function with an additional binding functionality may provide the desired enhancement of the host-guest affinity, yet for a different reason than that implemented by design as guided by standard molecular modeling. 相似文献
62.
Manisha U. Phadke Vivek K. Jadhav Rajendra K. Jadhav Suraj S. Dave Dattatray S. Patil 《Chromatographia》2008,68(11-12):1003-1007
A simple, fast and precise reversed phase liquid chromatographic method was developed for the simultaneous determination of artesunate (AS) and amodiaquine (AD) in combined pharmaceutical dosage form. Chromatographic separation of the two drugs was performed on a BDS Hypersil C18, 100 mm × 4.6 mm, 3 μm particle size column as stationary phase with a mobile phase comprising of phosphate buffer (pH 3.0 with orthophosphoric acid) and acetonitrile in the proportion of 50:40 (v/v), at a flow rate of 0.8 mL min?1 and UV detection at wavelength 210 nm for AS and 300 nm for AD using photo diode array detection. The proposed method was validated for specificity, accuracy, linearity, range, precision and was successfully applied to the simultaneous determination of AS and AD in the combined fixed dosage form without any excipient’s interference. 相似文献
63.
Sanjay Jadhav Gajanan Rashinkar Rajashri Salunkhe Arjun Kumbhar 《Tetrahedron letters》2017,58(33):3201-3204
A simple, efficient and metal-free route for the synthesis of dissymmetric ketones through Suzuki type cross-coupling reaction has been established. This strategy signifies an attractive, cost-effective and operationally convenient tool for the synthesis of a wide range of dissymmetric ketones. Although conventional routes for the synthesis of ketones have been widely used, the potential challenge with these methods is functional group tolerance. The reported metal-free method represents a reaction with moderate functional group tolerance. The procedure is operationally convenient and shows broad substrate scope with good to excellent product yields. 相似文献
64.
Amol Maruti Jadhav Sandip Gangadhar Balwe Jong Su Kim Kwon Taek Lim Yeon Tae Jeong 《Tetrahedron letters》2019,60(7):560-565
An efficient, inexpensive and environmentally friendly synthesis of novel 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 3-amino-2-benzoyl-1-aryl-1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives has been developed via one-pot three-component reaction of phthalhydrazide or maleic hydrazide, aldehydes and arylacetonitrile in the presence of catalytic amount of InCl3 as a Lewis acid catalyst under solvent-free conditions. The most important features of the present protocol are mild reaction conditions, short reaction times, high yields, and a wide range of functional group tolerance. 相似文献
65.
Jagannath Jadhav Sharanabasappa KhanapaureRajanikant Kurane Rajashri SalunkheGajanan Rashinkar 《Tetrahedron letters》2013
An unprecedented methodology for the facile synthesis of 2-substituted 3-cyano-4-azaindoles using modified Madelung synthesis is described. The methodology relies on acid and amine coupling under very mild conditions. 相似文献
66.
Structural, electrical and magnetic characterizations of Ni-Cu-Zn ferrite synthesized by citrate precursor method 总被引:1,自引:0,他引:1
P.A. Jadhav 《Journal of Physics and Chemistry of Solids》2009,70(2):396-400
Fine powders of NiCuZn ferrite with composition Ni(0.7−x)CuxZn0.3Fe2O4 (where x=0, 0.2, 0.4 and 0.6) were prepared by the citrate precursor method. X-ray diffraction measurements confirm the formation of single-phase cubic spinel structure. The grain size was estimated by SEM micrograph which increases with Cu content. Dielectric constant (?) and loss tangent (tan δ) were measured as a function of frequency. The ? and tan δ show a decreasing trend with increase of frequency for all the samples. The DC resistivity was measured as a function of temperature. The temperature-dependent DC resistivity measurements show that the room-temperature DC resistivity of NiCuZn ferrite with x=0.2 is of the order of 109 Ω cm. The AC conductivity (σAC) was studied as a function of frequency. The hysteresis data indicate that the maximum saturation magnetization of 38.66 emu/g is obtained for the composition with x=0.2. 相似文献
67.
Rane Vipul P. Patil Rushikesh H. Patil Kiran R. Pathan Amin R. Naik Sukantakumar Ahirrao Vinod K. Jadhav Rajiv A. Yeole Ravindra D. 《Chromatographia》2022,85(2):155-165
Chromatographia - WCK 771 is a novel antibacterial drug recently launched in India for the treatment of acute bacterial skin and skin structure infections (ABSSSI). This report describes... 相似文献
68.
Vinod K. Ahirrao Rajiv A. Jadhav Suyog N. Vaidya Sachin S. Bhagwat Ravindra D. Yeole Mahesh V. Patel 《Biomedical chromatography : BMC》2022,36(6):e5354
Antibiotic susceptibility test (AST) discs are used as an in-vitro diagnostic tool to select the appropriate antibiotic to treat an infection. Generally, the concentration of the drug loaded on to the AST discs is measured by studying its activity against quality control organisms. This methodology has several limitations—it is time consuming, requires trained manpower, has a wider acceptance criteria of zone of inhibitions—causing ambiguity in judging smaller variations in drug concentration. To overcome these issues, we have developed and validated high-performance liquid chromatographic (HPLC) methods for the determination of strength of AST discs for in-house researched antibiotics, namely Levonadifloxacin/WCK 771, Nafithromycin/WCK 4873, Cefepime-Tazobactam/WCK 4282, and Cefepime-Zidebactam/WCK 5222. The drugs were extracted from the AST discs using an appropriate solvent. The developed methods are simple, accurate, precise, reproducible, rugged, and robust. They are efficient in terms of time, and can be easily conducted in a quality control laboratory during release as well as stability evaluation of AST disc. Application of HPLC methods for the determination of strength of AST discs ensures flawless quality and, consequently, a better selection of drugs to treat bacterial infections in clinics. 相似文献
69.
Keshav Chander S. P. Hasilkar A. V. Jadhav H. C. Jain 《Journal of Radioanalytical and Nuclear Chemistry》1993,174(1):127-132
A method for the sequential determination of thorium and uranium has been developed. In the sample solution containing thorium and uranium, thorium is first determined by complexometric titration with ethylenediaminetetraacetic acid (EDTA) and then in the same solution uranium is determined by redox titration employing potentiometry. As EDTA interferes in uranium determination giving positive bias, it is destroyed by fuming with HClO4 prior to the determination of uranium. A precision and accuracy of better than ±0.15% is obtained for thorium at 10mg level and uranium ranging from 5 mg to 20 mg in the aliquot. 相似文献
70.
The structural phase transition from orthorhombic (T) phase to tetragonal (T′) phase in substituted La2−x
R
x
CuO4 (R = Pr, Nd, Sm, Eu and Gd) and T′ to T-phase in Pr2−x
M
x
CuO4−y
(M = Sr, Ca) has been studied by X-ray diffraction technique. The T-phase of La2CuO4 is transferred to T′ phase abruptly atx=0.8, 0.4, 0.4, 0.3 and 0.4 respectively for substitution of Pr, Nd, Sm, Eu and Gd for La in La2CuO4 without evidence of the T* phase. The T′ structure of Pr2CuO4 (x = 0.0) gets transformed to the T* structure at 30% Ca doping (x=0.6) and then to the T structure at 50% Ca doping (x=1.0), while for Sr-contentx=0.0, 0.4 and 1.0 it shows T′, T* and T structure respectively. 相似文献