BACKGROUND: THE COMPUTATIONAL STUDIES ON COMFORMTIONAL ANALYSIS OF ORGANIC COMPOUNDS HAVE BEEN OF INTEREST FOR CHEMISTS IN RECENT DECADES [1-3]. THE STRUCTURE OF PYRIDINE DICARBOXYLIC ACID HAS BEEN RECENTLY STUDIED BY CRYSTALLOGRAPHIC DATA. IT HAS BEEN SHOWN THAT THE MOLECULE EXIST AS DIMMER IN CRYSTAL STATE. THE COMPLEXES OF THIS COMPOUND WITH DIFFERENT METALS HAVE ALSO BEEN EXTENSIVELY STUDIED.METHODS: THE COMPUTATIONAL STUDIES HAS BEEN DONE USING B3LYP METHOD WITH 6-311++G** BASIS SET. THE GAUSSIAN 09 PACKAGE HAS BEEN USED FOR COMPUTATIONS. THE OPTIMIZATION AND ENERGY AND FREQUENCY CALCULATIONS HAVE ALL BEEN DONE USING THIS LEVEL OF COMPUTATION.RESULTS: THE MOST STABLE CONFORMATION OF PYRIDINE DICAROXYLIC ACID HAS BEEN SHOWN TO BE AS BELOW. STRUCTURE A WAS CALCULATED TO BE THE MOST STABLE CONFORMER OF PYRIDINE-2, 6-DICARBOXYLIC ACID. STRUCTURE C IS THE MOST STABLE CONFORMER OF PYRIDINE-2, 3-DICARBOXYLIC ACID. WE ALSO CALCULATED THE RELATIVE-ENERGY FOR DIMER OF THIS COMPOUND AND THE MOST STABLE STRICTURE WAS CALCULATED AS SHOWN IN SCHEME BELOW (STRUCTURE B). THIS CALCULATED STRUCTURE IS IN GOOD AGREEMENT WITH CRYSTALLOGRAPHIC DATA.

POLYESTERS, MAINLY POLY (ETHYLENE TEREPHTHALATE) (PET), ARE NOW WIDELY USED FOR TEXTILE FIBERS, TECHNICAL FIBERS, FILMS, AND BOTTLES. COPOLYMERIZATION AND COMPOUNDING IS A REASONABLE METHOD FOR IMPROVING THE PROPERTIES OF PET. 2, 6- NAPHTHALENEDICARBOXYLIC ACID (NDA) IS ONE OF THE MOST IMPORTANT COMONOMERS FOR PET. IN THIS RESEARCH, PET AND PET COPOLYMERS CONTAINING 3-5% NDA WERE PREPARED FROM COMONOMER MIXTURES BY TWO-STEP MELT POLYCONDENSATION IN PRESENCE OF ANTIMONY-BASED CATALYST. THE COPOLYMERS WERE SYNTHESIZED IN A HOMEMADE LABORATORY SETUP. THE MICROSTRUCTURE OF THE SYNTHESIZED POLYMERS WAS STUDIED WITH FOURIER TRANSFORM INFRARED (FTIR). DIFFERENTIAL SCANNING CALORIMETRY (DSC) WAS USED TO STUDY THE THERMAL PROPERTIES OF THE COPOLYMERS TO DETECT CHANGES IN THE POLYMER PROPERTIES. INTRINSIC VISCOSITY OF FINAL PRODUCED PET AND PET COPOLYMERS HAVE BEEN INVESTIGATED. THE DSC RESULTS HAVE SHOWN THAT THE MODIFICATION OF PET WITH LOW LEVELS OF NAPHTHALATE COMONOMER INCREASES THE TG AND THIS PROPERTY HAS A SIGNIFICANT EFFECT ON THE THERMAL STABILITY POTENTIAL OF MANY HOT, AQUEOUS EXPOSURE APPLICATIONS AND ORIENTED ARTICLES (FILMS, FIBERS, CONTAINERS, ETC.) TO RESIST HIGHER TEMPERATURES WITHOUT SHRINKAGE. BASED ON THE FTIR RESULT, THE SYNTHESIZED COPOLYMER IS POLY (ETHYLENE TEREPHTHALATE-CO-2, 6-NAPHTHALENEDICARBOXYLIC ACID). ON THE OTHER HAND, PET COPOLYMER HAD A LOWER IV THAN THE SYNTHESIZED PET.

THE VANADIUM REDOX FLOW BATTERY (VRB) IS ONE OF THE MOST PROMISING ELECTROCHEMICAL ENERGY STORAGE SYSTEMS DEEMED SUITABLE FOR A WIDE RANGE OF RENEWABLE ENERGY APPLICATIONS THAT ARE EMERGING RAPIDLY TO REDUCE THE CARBON FOOTPRINT OF ELECTRICITY GENERATION. TYPICALLY, EACH CELL COMPRISES OF AN ANODE, A CATHODE AND AN ION EXCHANGE MEMBRANE SEPARATOR THAT ALLOWS DIFFUSION OF IONS ACROSS THE MEMBRANE WHILE PREVENTING THE CROSS-MIXING OF THE ELECTROLYTE SOLUTIONS FROM THESE TWO RESERVOIRS. REDOX FLOW BATTERIES HAVE MANY TECHNICAL BENEFITS OVER OTHER ENERGY STORAGE SYSTEMS; THEY REPRESENT AN EXCELLENT COMBINATION OF ENERGY EFFICIENCY, CAPITAL COST AND LIFE CYCLE COSTS WHEN COMPARED TO OTHER TECHNOLOGIES.IN THIS WORK SOME OF SHORT CHAIN DICARBOXYLIC ACIDS WERE ADDED TO CATHOLYTE OF VRFB TO IMPROVE THE ELECTROCHEMICAL BEHAVIOR OF V (V) /V (IV) REDOX COUPLES. THESE ADDITIVES WERE OXALIC ACID AND SUCCINIC ACID. CYLIC VOLTAMMETRY, ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY TECHNIQUES WERE USED TO INVESTIGATE THE EFFECT OF THESE ADDITIVES. ACCORDING TO THE RESULTS OF EXPERIMENTS OXALIC ACID AND SUCCINIC ACID HAD BETTER PERFORMANCE IN COMPARISON WITH THE BLANK ELECTROLYTE, RESPECTIVELY.

URANIUM IS A SILVERY-WHITE METALLICCHEMICAL ELEMENT IN THE ACTINIDE SERIES OF THE PERIODIC TABLE, WITH SYMBOL U AND ATOMIC NUMBER 92. U IS WEAKLY RADIOACTIVE BECAUSE ALL ITS ISOTOPES ARE UNSTABLE. THE MOST COMMON ISOTOPES OF URANIUM ARE URANIUM-238AND URANIUM-235. URANIUM HAS THE SECOND HIGHEST ATOMIC WEIGHT OF THE PRIMORDIALLY OCCURRING ELEMENTS, LIGHTER ONLY THAN PLUTONIUM. U HAS A MELTING POINT IS 1132°C. U IS A NATURALLY OCCURRING RADIOACTIVE ELEMENT WHICH IS IMPORTANT FOR NUCLEAR TECHNOLOGY. HOWEVER, MINERAL RESOURCES FOR URANIUM ARE LIMITED [1]. OVER 13% OF THE WORLD'S ELECTRICITY IS GENERATED FROM URANIUM IN NUCLEAR REACTORS. THIS CIRCUMSTANCE IS BEING TO DEVELOP IN THE RECENT YEARS AND HAS BEEN BEGAN TO PROGRESS IN THE THIRD-WORLD COUNTRIES [2].PYRIDINE-2, 6-DICARBOXYLIC ACID (PDA) IS A WHITE CRYSTAL LINE POWDER THAT CAPABLE TO PRODUCE HIGH STABLE CHELATES WITH MANY OF METAL IONS RESPECTING TO PH OF THE SOLUTION. IN SPITE OF THIS CAPABILITY, ALMOST OF ITS METAL CHELATE ARE NOT ACTIVE IN PHOTOLUMINESCENCE SPECTROSCOPY. OUR INVESTIGATION SHOWED THAT AMONG THE VARIOUS METAL IONS U (VI) IS CAPABLE TO PRODUCE A HIGH STABLE CHELATE WITH PDA, WHICH ITS SYNTHESIS CAN BE READILY DETECTED BY FLUORESCENCE SPECTROPHOTOMETRY. THIS FUTURE RESULTED IN PRESENCE OF A RAPID AND SENSITIVE METHOD FOR THE DETERMINATION OF TRACE AMOUNTS OF URANIUM IN WATER SAMPLES. THE ANALYTICAL PROCEDURE IS BASED ON THE MEASUREMENT OF THE FLUORESCENCE PRODUCED FROM THE COMPLEX FORMED BETWEEN U (VI) AND PDA. THE FLUORESCENCE INTENSITY OF THE SYSTEM REMARKABLY WAS MUCH GREATER THAN THAT OF THE SYSTEM WITHOUT U (VI). THE OPTIMUM CONDITIONS FOR THIS PROCEDURE WAS INVESTIGATED INCLUDING PDA CONCENTRATION OF 5×10-5 MOL/L, PH (ACETIC ACID-SODIUM ACETATE BUFFER). THE PROPOSED METHOD WAS APPLIED SUCCESSFULLY TO THE DETERMINATION OF TRACE AMOUNT OF U (VI) IN THE RANGE OF 5 ´ 10-7 TO 1 ´10-5 MOL/L IN WATER SAMPLES. THE DETECTION OF LIMIT AND% RSD ARE 58 NM AND 2.16 RESPECTIVELY. THE SELECTIVITY OF THE PROPOSED METHODOLOGY WAS SURVEYED BY STUDYING INTERFERENCE EFFECTS ON THE ANALYTICAL RESPONSE. THE CO-EXISTING IONS IN WATER SAMPLE INCLUDING MG, K, NA, NH4, NO3 AND SO4 WERE NOT INTERFERED IN THIS DETERMINATION. THE INTERFERENCE OF THE OTHER CO-EXISTENCE METAL IONS WAS READILY ELIMINATED BY MASKING WITH EGTA REAGENT. THIS METHOD CAN BE CONSIDERED ONE OF THE MOST SENSITIVE AND SELECTIVE METHODS FOR THE DETERMINATION OF URANIUM.

WE HAVE BEEN CONCERNED WITH THE SYNTHESIS OF WATER-SOLUBLE PROTON-TRANSFER SELF-ASSOCIATED SYSTEMS THAT CAN FUNCTION AS SUITABLE LIGANDS IN THE SYNTHESIS OF METAL-ORGAN OCOMPOUNDS. THE APPROACH THAT WE HAVE APPLIED IS BASED ON THE PROTON TRANSFER PROCESSES BETWEEN APPROPRIATE CARBOXYLIC ACIDS AND AMINES AND THE FACT THAT ION- PAIRING AND INTERMOLECULAR FORCES CAN PROVIDE A LARGE PART OF THE STABILIZATION ENERGY OF THE RESULTING SELF-ASSOCIATED SYSTEMS [1, 2]. IN THIS PAPER THE SYNTHESIS OF A CRYSTALLINE SELF-ASSOCIATED SYSTEM [BAH]4[(PYDCH)2(PYDC)].PYDCH2 IS REPORTED. THE PROTON TRANSFER COMPOUND WAS PREPARED BY A REACTION BETWEEN PYRIDINE-2,6- DICARBOXYLIC ACID, PYDCH2, AND BENZYL AMINE, BA, IN 1:2 MOLAR RATIO. TO A SOLUTION OF BA (45 MMOL, 4.90 G) IN THF (10 ML) WAS ADDED A SOLUTION OF PYDCH2 (22.5 MMOL, 3.75 G) IN THF (500 ML). COLORLESS CRYSTALS OF OUR COMPOUND WERE OBTAINED FROM THIS MIXTURE AFTER 20 DAYS. THIS COMPOUND WAS CHARACTERIZED BY IR, 1H NMR AND 13C NMR SPECTROSCOPY, ELEMENTAL ANALYSES AND X-RAY CRYSTALLOGRAPHY. THE MOST IMPORTANT FEATURES OF THE CRYSTAL STRUCTURE OF THIS COMPLEX ARE THE INTERACTIONS BETWEEN FRAGMENTS CONSISTING OF ION-PAIRING AND HYDROGEN BONDING AND CONSEQUENTLY IT CAN BE CONSIDERED AS A SUPRAMOLECULAR STRUCTURE FORMED BY NON-COVALENT INTERACTIONS.

THE CROSS-COUPLING REACTIONS OF ARYL HALIDES WITH ARYLBORONIC ACIDS, OFTEN REFERRED TO SUZUKI-MIYAURA COUPLING REACTIONS, ARE VERSATILE METHODS FOR SYNTHESIZING UNSYMMETRICAL BIARYLS, WHICH HAVE A CRUCIAL ROLE IN NATURAL PRODUCTS AND PHARMACEUTICAL COMPOUNDS. ...

THE HETEROCYCLIC AROMATIC COMPOUND, 8-HYDROXYQUINOLINE (8HQ) IS OFTEN FOUND AN ENVIRONMENTAL POLLUTANT DUE TO ITS WIDESPREAD USE IN INDUSTRY, MEDICINE AND AGRICULTURE [1]. IN THIS STUDY WE REPORT SYNTHESIS AND CHARACTERIZATION OF [VO2(DIPIC)][BA(HQ)(H2O)5] COMPLEX THAT (DIPIC = 2,6- PYRIDINE DICARBOXYLIC ACID) AND (HQ= 8-HYDROXYQUINOLIN).THIS COMPLEX CHARACTERIZED USING FT-IR, UV-VIS, AND CYCLIC VOLTAMMETER METHOD. THE BANDS IN 565, 472, 467 AND 521 CM-1 ATTRIBUTED TO BA-O, BA-N, V-N AND V-O RESPECTIVELY [2]. ELECTRONIC SPECTRUM SHOW CHARGE TRANSFER (LMCT) TRANSITION. THE BANDS IN UV REGION, AROUND 212- 270 NM WERE ASSIGNED TO INTRA LIGAND TRANSITIONS OF LIGAND AND BANDS AT 239 AND 335 NM ARE RELATED TO P ® P * AND N ® P* TRANSITIONS OF HQ RESPECTIVELY [3]. CYCLIC VOLTAMETERY DATA SHOW SEVERAL QUASI-REVERSIBLE WAVES ATTRIBUTED TO BOTH LIGANDS AND ION METAL [4].