Regioselective Synthesis of Quinazolinone‐/Phenanthridine‐Fused Heteropolycycles by Pd‐Catalyzed Direct Intramolecular Aerobic Oxidative C−H Amination from Aromatic Strained Amides

A new route for the expedient synthesis of specific regioisomer of quinazolinone‐ and phenanthridine‐fused heterocycles through a palladium‐catalyzed regioselective intramolecular oxidative C?H amination from cyclic strained amides of aromatic amido–amidine systems (quinazolinones) has been developed. The amine functionalization of an aromatic C?H bond from a strained amide nitrogen involved in aromaticity has been a challenging work so far. The fusion of two heterocyclic cores, quinazolinone and phenanthridine, can occur in two different ways (linear and angular), but under the conditions reported here, only linear type isomer is exclusively produced. This approach provides a variety of substituted quinazolinone‐ and phenanthridine‐fused derivatives in moderate to excellent yields. Moreover, such fused molecules show excellent fluorescent properties and have great potential to be a new type of fluorophores for the use in medicinal and material science.     

Mass Spectrometry Based Mechanistic Insights into Formation of Tris Conjugates: Implications on Protein Biopharmaceutics

We present here extensive mass spectrometric studies on the formation of a Tris conjugate with a therapeutic monoclonal antibody. The results not only demonstrate the reactive nature of the Tris molecule but also the sequence and reaction conditions that trigger this reactivity. The results corroborate the fact that proteins are, in general, prone to conjugation and/or adduct formation reactions and any modification due to this essentially leads to formation of impurities in a protein sample. Further, the results demonstrate that the conjugation reaction happens via a succinimide intermediate and has sequence specificity. Additionally, the data presented in this study also shows that the Tris formation is produced in-solution and is not an in-source phenomenon. We believe that the facts given here will open further avenues on exploration of Tris as a conjugating agent as well as ensure that the use of Tris or any ionic buffer in the process of producing a biopharmaceutical drug is monitored closely for the presence of such conjugate formation.

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Unusual spectral renormalization in hexaborides

Employing high resolution photoemission spectroscopy, we studied the evolution of the spectral features in rare earth hexaboride single crystals as a function of temperature and 4f binding energy, where the variation of the 4f binding energy is obtained by changing the rare earth element. High energy resolution helped to reveal the distinct features corresponding to the various photoemission final states. Experimental results of CeB(6), a dense Kondo system, exhibit the growth of the features near the Fermi level with the decrease in temperature relative to the uncompensated local moment contributions. The valence band spectra of the antiferromagnetic compounds, PrB(6) and NdB(6), exhibit multiple features-the 4f ionization peaks (poorly screened features) appear at higher binding energies and the features in the vicinity of the Fermi level possessing significant 4f character are due to the well-screened photoemission final states. These results indicate finite hybridization between the 4f and B 2s2p conduction electronic states. Interestingly, the well-screened features in PrB(6) and NdB(6) exhibit unusual enhancement in intensity at low temperature.     

Substituent effects on Ni-S bond dissociation energies and kinetic stability of nickel arylthiolate complexes supported by a bis(phosphinite)-based pincer ligand

Pincer complexes of the type [2,6-(R(2)PO)(2)C(6)H(3)]NiSC(6)H(4)Z (R = Ph and i-Pr; Z = p-OCH(3), p-CH(3), H, p-Cl, and p-CF(3)) have been synthesized from [2,6-(R(2)PO)(2)C(6)H(3)]NiCl and sodium arylthiolate. X-ray structure determinations of these thiolate complexes have shown a somewhat constant Ni-S bond length (approx. 2.20 ?) but an almost unpredictable orientation of the thiolate ligand. Equilibrium constants for various thiolate exchange (between a nickel thiolate complex and a free thiol, or between two different nickel thiolate complexes) reactions have been measured. Evidently, the thiolate ligand with an electron-withdrawing substituent prefers to bond with "[2,6-(Ph(2)PO)(2)C(6)H(3)]Ni" rather than "[2,6-(i-Pr(2)PO)(2)C(6)H(3)]Ni", and bonds least favourably with hydrogen. The reactions of the thiolate complexes with halogenated compounds such as PhCH(2)Br, CH(3)I, CCl(4), and Ph(3)CCl have been examined and several mechanistic pathways have been explored.     

Studies of the effect of variation of blend ratio on permselectivity and heterogeneity of ion-exchange membranes

Heterogeneous ion-exchange membranes (both cationic and anionic types) have been synthesized by solution casting techniques using polyvinyl chloride (PVC) as binder and ion-exchange resin (-300+400 mesh). The binder:resin ratio varied from 60:40 to 30:70. The transport behavior of the membranes has been evaluated chronopotentiometrically in sodium chloride (NaCl) solutions of different concentrations. The different parameters E(0) (potential drop across the membrane at the instant of application of current I), E(max) (maximum potential drop across the membrane after the application of current I), DeltaE (magnitude of the potential jump across the membrane at transition time tau), Itau(1/2), tau, etc., have been evaluated. The isoconductance points were determined and based on the microheterogeneous model proposed by Zabolotsky and Nikonenko (J. Membrane Sci. 79 (1993) 181) the distribution factors beta has been evaluated for both types of ion exchange membranes. The electroconductivity of the joint gel (kappa ) and pure gel phases (kappa ' ) has been determined. At any particular solution concentration the transport number as well as the permselectivity of membranes increases with increased resin content of the membrane. The microheterogeneity factor beta exhibits synchronization among the each set of four different membranes for both the cationic and anionic type.     

Mechanistic variations in ionic hydrogenation of unsaturated phosphine and amine boranes

Internal hydride transfer occurs when tethered carbocations are generated from unsaturated phosphine or phosphinite boranes. 3-Methylenecyclohexyl-derived boranes 12 or 18 react with MsOH to give ionic hydrogenation products with high syn-selectivity. With unsaturated amine boranes, initial hydrogen evolution gives BH(2)(OMs) complexes, but IH occurs using excess MsOH in a slower second stage. A diastereoselective reaction occurs from 26b using camphorsulfonic acid (first stage) and MsOH (second stage), affording 33 (68% ee) after hydrolysis.     

A simulation based method to assess inversion algorithms for transverse relaxation data

NMR relaxometry is a very useful tool for understanding various chemical and physical phenomena in complex multiphase systems. A Carr-Purcell-Meiboom-Gill (CPMG) [P.T. Callaghan, Principles of Nuclear Magnetic Resonance Microscopy, Clarendon Press, Oxford, 1991] experiment is an easy and quick way to obtain transverse relaxation constant (T₂) in low field. Most of the samples usually have a distribution of T₂ values. Extraction of this distribution of T₂s from the noisy decay data is essentially an ill-posed inverse problem. Various inversion approaches have been used to solve this problem, to date. A major issue in using an inversion algorithm is determining how accurate the computed distribution is. A systematic analysis of an inversion algorithm, UPEN [G.C. Borgia, R.J.S. Brown, P. Fantazzini, Uniform-penalty inversion of multiexponential decay data, Journal of Magnetic Resonance 132 (1998) 65–77; G.C. Borgia, R.J.S. Brown, P. Fantazzini, Uniform-penalty inversion of multiexponential decay data II. Data spacing, T₂ data, systematic data errors, and diagnostics, Journal of Magnetic Resonance 147 (2000) 273–285] was performed by means of simulated CPMG data generation. Through our simulation technique and statistical analyses, the effects of various experimental parameters on the computed distribution were evaluated. We converged to the true distribution by matching up the inversion results from a series of true decay data and a noisy simulated data. In addition to simulation studies, the same approach was also applied on real experimental data to support the simulation results.     

Flexible hybrid eu3+ doped P(VDF‐HFP) nanocomposite film possess hypersensitive electronic transitions and piezoelectric throughput

A novel red light‐emitter made of Eu³⁺ doped self‐poled electroactive poly(vinylidene fluoride–hexafluoropropylene) [P(VDF‐HFP)] hybrid nanocomposite film possesses piezoelectric throughput that is suitable for flexible piezoelectric nanogenerator (PNG) fabrication. We observed that PNG is enabled to generate an open‐circuit voltage of 5 V and 0.35 μA of short‐circuit current under an applied pressure amplitude of ～10.4 kPa. By simple mechanical energy scavenging, PNG demonstrates an ability to light more than ten blue commercial light emitting diodes instantly, without using an energy‐storage device. Additionally, it successfully charges up capacitors by simple repeating finger touch motion, which indicates its potency as an efficient energy harvesting power source. The high performance of PNG is due to well‐coated Eu³⁺ with P(VDF‐HFP) in a hybrid nanocomposite so it displays improved dielectric permittivity and energy storage capacity. This flexible composite film also possesses a hypersensitive electronic transition as it responds by an intense red light‐emission confirmed by the CIE 1931 chart. This enables applications in piezo‐photonics as a high‐performance, energy‐saving, flexible solid‐state red light emitter. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2335–2345.     

Radical transfer reactions in polymers

Free-radical transfer in polymers have been studied by pulse radiolysis and product analysis with the water-soluble polymers poly(vinyl alcohol), poly(acrylic acid), poly(methacrylic acid), polynucleotides and DNA. When OH radicals react with polymers the lifetime of the polymer radical thus created strongly depends on the number of radicals per polymer chain. Moreover, in negatively charged polymers the increased stiffness at high pH results in a remarkable increase of the lifetime of the radicals with respect to recombination. This allows a number of radical transfer reactions to occur (e.g. intramolecular H-transfer, β-fragmentation, depolymerization, reactions with additives).