Controlled trapping of single particle states on a periodic substrate by deterministic stubbing

A periodic array of atomic sites, described within a tight binding formalism is shown to be capable of trapping electronic states as it grows in size and gets stubbed by an ‘atom’ or an ‘atomic’ clusters from a side in a deterministic way. We prescribe a method based on a real space renormalization group method, that unravels a subtle correlation between the positions of the side coupled atoms and the energy eigenvalues for which the incoming particle finally gets trapped. We discuss how, in such conditions, the periodic backbone gets transformed into an array of infinite quantum wells in the thermodynamic limit. We present a case here, where the wells have a hierarchically distribution of widths, hosting standing wave solutions in the thermodynamic limit.     

Vesicle Formation from an Amphiphilic Porphyrin Derivative at the Air–Water Interface

A tetraphenyl porphyrin derivative with two C₁₆ alkyl chains covalently bound to each of the four peripheral phenyl rings through ether linkages formed multilayer clusters or vesicles at the air–water surface. More interestingly, spherical vesicles were also formed when deposited on appropriate solid surfaces, and these vesicles were stable even in dry conditions. Various microscopic images of the cast film deposited on a mica surface confirmed closed‐ended nanotube/nanorod‐type formation with necking and bulging. These narrow tubes are proposed to be intermediates for the formation of vesicles by fission at either side of the bulge. Such vesicular formation is not common when either cast or Langmuir–Blodgett films were deposited on a solid surface.     

Thioester hydrolysis reactivity of zinc hydroxide complexes: investigating reactivity relevant to glyoxalase II enzymes

A recently reported binuclear zinc hydroxide complex [(L(1)Zn(2))(mu-OH)](ClO(4))(2) (, L(1) = 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenolate monoanion) containing a single bridging hydroxide was examined for thioester hydrolysis reactivity. Treatment of it with hydroxyphenylthioacetic acid S-methyl ester in dry CD(3)CN results in no reaction after approximately 65 h at 45(1) degrees C. Binuclear zinc hydroxide complexes of the N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine (L(2)) and N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)ethyl)amine (L(3)) chelate ligands were prepared by treatment of each ligand with molar equivalent amounts of Zn(ClO(4))(2).6H(2)O and KOH in methanol. These complexes, [(L(2)Zn)(2)(mu-OH)(2)](ClO(4))(2) and [(L(3)Zn)(2)(mu-OH)(2)](ClO(4))(2) (), which have been structurally characterized by X-ray crystallography, behave as 1 : 1 electrolytes in acetonitrile, indicating that the binuclear cations dissociate into monomeric zinc hydroxide species in solution. Treatment of them with one equivalent of hydroxyphenylthioacetic acid S-methyl ester per zinc center in acetonitrile results in the formation of a zinc alpha-hydroxycarboxylate complex, [(L(2))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O or [(L(3))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O, and CH(3)SH. These reactions, to our knowledge, are the first reported examples of thioester hydrolysis mediated by zinc hydroxide complexes. The results of this study suggest that a terminal Zn-OH moiety may be required for hydrolysis reactivity with a thioester substrate.     

Role of positional isomers on receptor-anion binding and evidence for resonance energy transfer

New urea-based sensors show a strong affinity for F⁻, CH₃COO⁻, and H₂PO₄⁻ with an appreciable color change in the presence of excess F⁻. The position of the nitro group in the urea derivative influences the relative affinity toward anionic analytes. Spectral and ab initio studies showed the difference in the deprotonation sites for the ortho- and meta/para-isomers in these cases. Photophysical studies confirmed the resonance energy transfer in the case of the ortho-isomer. The ortho-isomer can act as a dual emission probe for F⁻.     

Photoinduced intramolecular charge transfer (ICT) reaction in trans-methyl p-(dimethylamino) cinnamate: A combined fluorescence measurement and quantum chemical calculations

The photophysical behaviour of trans-methyl p-(dimethylamino) cinnamate (t-MDMAC) donor–acceptor system has been investigated by steady-state absorption and emission spectroscopy and quantum chemical calculations. The molecule t-MDMAC shows an emission from the locally excited state in non-polar solvents. In addition to weak local emission, a strong solvent dependent red shifted fluorescence in polar aprotic solvents is attributed to highly polar intramolecular charge transfer state. However, the formation of hydrogen-bonded clusters with polar protic solvents has been suggested from a linear correlation between the observed red shifted fluorescence band maxima with hydrogen bonding parameters (). Calculations by ab initio and density functional theory show that the lone pair electron at nitrogen center is out of plane of the benzene ring in the global minimum ground state structure. In the gas phase, a potential energy surface along the twist coordinate at the donor (–NMe₂) and acceptor (–CH = CHCOOMe) sites shows stabilization of S₁ state and destabilization S₂ and S₀ states. A similar potential energy calculation along the twist coordinate in acetonitrile solvent using non-equilibrium polarized continuum model also shows more stabilization of S₁ state relative to other states and supports solvent dependent red shifted emission properties. In all types of calculations it is found that the nitrogen lone pair is delocalized over the benzene ring in the global minimum ground state and is localized on the nitrogen centre at the 90° twisted configuration. The S₁ energy state stabilization along the twist coordinate at the donor site and localized nitrogen lone pair at the perpendicular configuration support well the observed dual fluorescence in terms of proposed twisted intramolecular charge transfer (TICT) model.     

A Comprehensive Review on the Techniques for Extraction of Bioactive Compounds from Medicinal Cannabis

Cannabis is well-known for its numerous therapeutic activities, as demonstrated in pre-clinical and clinical studies primarily due to its bioactive compounds. The Cannabis industry is rapidly growing; therefore, product development and extraction methods have become crucial aspects of Cannabis research. The evaluation of the current extraction methods implemented in the Cannabis industry and scientific literature to produce consistent, reliable, and potent medicinal Cannabis extracts is prudent. Furthermore, these processes must be subjected to higher levels of scientific stringency, as Cannabis has been increasingly used for various ailments, and the Cannabis industry is receiving acceptance in different countries. We comprehensively analysed the current literature and drew a critical summary of the extraction methods implemented thus far to recover bioactive compounds from medicinal Cannabis. Moreover, this review outlines the major bioactive compounds in Cannabis, discusses critical factors affecting extraction yields, and proposes future considerations for the effective extraction of bioactive compounds from Cannabis. Overall, research on medicinal marijuana is limited, with most reports on the industrial hemp variety of Cannabis or pure isolates. We also propose the development of sustainable Cannabis extraction methods through the implementation of mathematical prediction models in future studies.     

In vitro and in vivo evaluation of β-cyclodextrin-based nanosponges of telmisartan

Telmisartan (TEL) is a BCS Class II drug having dissolution rate limited bioavailability. The aim of work was to enhance the solubility of TEL so that bioavailability problems are solved. β-Cyclodextrin (β-CD) based nanosponges (NSs) were formed by cross-linking β-CD with carbonate bonds, which were porous as well as nanosized. Drug was incorporated by solvent evaporation method. The effect of ternary component alkalizer (NaHCO₃) on solubility of TEL was studied. In order to find out the solubilization efficiency of NS, phase solubility study was carried out. Saturation solubility and in vitro dissolution study of β-CD complex of TEL was compared with plain TEL and NS complexes of TEL. The NS and NS complexes of TEL were characterized by differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, nuclear magnetic resonance and scanning electron microscope. It was found that solubility of TEL was increased by 8.53-fold in distilled water; 3.35-fold in 0.1 N HCl and 4.66-fold in phosphate buffer pH 6.8 by incorporating NaHCO₃ in drug–NS complex than TEL. It was found that the NaHCO₃ in NS based complex synergistically enhanced dissolution of TEL by modulating microenvironmental pH and by changing amorphization of the drug. The highest solubility and in vitro drug release was observed in inclusion complex prepared from NS and NaHCO₃. An increase of 54.4 % in AUC was seen in case the ternary NS complex whereas β-CD ternary complex exhibited an increase of 79.65 %.     

X-Ray Crystallographic Investigation of Fully Acetylated N-(2-Deoxy-2-Acetamido-β-D-Glucopyranosyl)Alkanamides as N-Glycoprotein Linkage Region Analogs

To understand the structural significance of the linkage region of N-glycoproteins, three title sugar amides have been prepared as analogs and their molecular assembly and crystal structures have been solved to explore the effect of acetyl protection and aglycon variation on the conformation, particularly of the N-glycosidic linkage. Comparative analysis of these structures with those of free sugar amides reported earlier showed that conformation of the amido aglycon moiety is not altered significantly by the masking of hydroxyl groups in the form of acetate. The bifurcated antiparallel pattern involving N?H…O and C?H…O hydrogen bonds, a hallmark of the N-glycoprotein models GlcNAcβNHAc and GlcNAcβAsn, is absent in all of the fully protected title alkanamides. The asymmetric unit of the tri-O-acetylated GlcNAcβNHAc contains two different conformations, in one of which the double-pillared hydrogen bond network involving C1 and C2 acetamido groups is antiparallel, while it is parallel in the other. The co-occurrence of a molecular assembly motif—a double-pillared parallel and antiparallel hydrogen bonding pattern—is hitherto unknown in the crystal structures of N-glycoprotein linkage region models and analogs.