Amine‐Responsive Adaptable Nanospaces: Fluorescent Porous Coordination Polymer for Molecular Recognition

Flexible and dynamic porous coordination polymers (PCPs) with well‐defined nanospaces composed of chromophoric organic linkers provide a scaffold for encapsulation of versatile guest molecules through noncovalent interactions. PCPs thus provide a potential platform for molecular recognition. Herein, we report a flexible 3D supramolecular framework {[Zn(ndc)(o‐phen)]?DMF}_n (o‐phen=1,10‐phenanthroline, ndc=2,6‐napthalenedicarboxylate) with confined nanospaces that can accommodate different electron‐donating aromatic amine guests with selective turn‐on emission signaling. This system serves as a molecular recognition platform through an emission‐readout process. Such unprecedented tunable emission with different amines is attributed to its emissive charge‐transfer (CT) complexation with o‐phen linkers. In certain cases this CT emission is further amplified by energy transfer from the chromophoric linker unit ndc, as evidenced by single‐crystal X‐ray structural characterization.     

Nonparametric estimation of location parameter after a preliminary test on regression in the multivariate case

For a simple multivariate regression model, nonparametric estimation of the (vector of) intercept following a preliminary test on the regression vector is considered. Along with the asymptotic distribution of these estimators, their asymptotic bias and dispersion matrices are studied and allied efficiency results are presented.     

The Spearman footrule and a Markov chain property

An equivalent representation of the Spearman footrule is considered and a characterization in terms of a Markov chain is established. A martingale approach is thereby incorporated in the study of the asymptotic normality of the statistics.     

Extractive Spectrophotometric Determination of Titanium in Silicate Rocks, Soils and Columbite–Tantalite Minerals

2,3-Dihydroxynaphthalene forms a strong chelate with titanium over the pH range 4 to 9. At pH 4–5, titanium is extracted into ethyl acetate along with iron, leaving behind V, Nb, Mo, and a host of elements present in complex matrices of rock samples. In the extract, titanium is easily separated from iron after raising the pH of the medium and re-extracting. The method is free from any interference. The sensitivity of the method is 3.2×10⁴ L·mol^–1cm^–1. The method has been applied to a number of diverse samples including rocks and minerals. The precision of the Ti method is excellent. This method has been compared with tiron, chromotropic acid, diantipyrilmethane (DAM) and other existing spectrophotometric methods used in the analysis of rocks, ores and minerals. The proposed method has definite advantages over most spectrophotometric methods in terms of sensitivity, selectivity, reproducibility and simplicity.     

Stereocontrol of 1,5-related stereocentres using an intermediate silyl group--the diastereoselectivity of nucleophilic attack on a double bond adjacent to a stereogenic centre carrying a silyl group

R-5-Methylcyclohex-2-enone 1 reacts successively with the phenyldimethylsilylzincate reagent and acetaldehyde to give with regiocontrol the aldols 7, dehydration of which creates the E-exocyclic double bond of the alpha,beta-unsaturated ketone 2. Conjugate addition of the ethylcuprate reagent to this compound takes place with high (96:4) selectivity in favour of the R stereoisomer 12, hydrolysis of which gives (2R,3R,5S,2'R)-2-(but-2'-yl)-3-dimethyl(phenyl)silyl-5-methylcyclohexanone 3. The oxime acetate of this ketone undergoes fragmentation in the presence of trimethylsilyl trifluoromethanesulfonate to give 3R,7R,5E-3,7-dimethylnon-5-enonitrile 4, in which an open-chain 1,5-stereochemical relationship is set up with a high level of stereocontrol. A similar sequence adding 4-methylpentylcuprate to the enone 2, and fragmentation gives 3R,7R,5E-3,7,11-trimethyldodec-5-enonitrile 20. Reduction and hydrogenation of this nitrile gives 3R,7R-3,7,11-trimethyldodecanal 22, which can be converted into phytol 25. The ketoaldehyde 29 reacts with samarium iodide to give only the alcohol 30, in which the radical anion has attacked from the top surface just like the cuprate reagents in their reactions with the ketone 2.     

Study on typical behavior of transient nature (I-t) and hysterisis nature of I–V characteristics of dye doped solid state thin film photoelectrochemical cell

In this present investigation, we describe the steady state current voltage (I–V) characteristic of Crystal violet dye dispersed solid state photoelectrochemical cell (PEC). Typical behavior of dark current-voltage characteristic by increasing and decreasing external bias voltage has a similar form like hysterisis in nature. Although we have already observed this hysterisis nature in case of both forward and reverse bias condition, yet it is clear that the reverse hysterisis curve is more prominent than forward hysterisis. In this paper, we are getting double values of current (I) for a single value voltage, which is also helpful to understand the charge transport process through disordered materials. As the bias increases, the distribution of traps depth, which is exponential in nature, changes toward order state (resulting increase in disordered parameter α) This means that as α increases, it tends to reach the most order state of material. When external bias voltage is at 3.5 V, the value of disorder parameter becomes 1, and when bias voltage is beyond 3.5 V, the diffusion comes enhanced in nature.     

Azimuthal correlation and fractal study of compound hadrons (pions and protons) at Dubna and SPS energy

This paper presents an investigation of compound hadrons (pions and protons) distribution emitted from ²⁴Mg-AgBr and ¹²C-AgBr interactions both at 4.5 AGeV and ³²S-AgBr interactions at 200 AGeV. The study includes azimuthal correlations (two particle and three particle), azimuthal asymmetry and fractal behaviour. This paper reveals some interesting results.     

Chemoselective reduction of a lactam carbonyl group in the presence of a gem-dicarboxylate by sodium borohydride and iodine: a facile entry to N-aryl trisubstituted pyrroles

Several N-aryl γ-lactam gem dicarboxylates were chemoselectively reduced to cyclic amine diesters by using sodium borohydride-iodine system. The reduction in all cases was completed within 2.5 h after refluxing in THF. The cyclic amine products were isolated after aqueous (acidic) workup in good yields. Hydrolytic decarboxylation followed by dehydrogenation produced N-aryl carboethoxy pyrroles.