Comparative photophysical behaviour of naphthalene-linked crown ethers and aza crown ethers of varying cavity dimensions

A comparative time-resolved emission studies of several naphtho-crown ethers I–V, where metal ions can be complexed in a predetermined orientation with respect to the naphthalene (Naph) π-plane and naphthalene-linked aza crown ethers (L1 and L2) have been presented. In both the systems, crown ethers and aza crown ethers, naphthalene fluorescence gets quenched. In the systems I to V, the quenching is mainly due to efficient spin-orbit coupling (SOC) leading to greater population of the lowest triplet state of naphthalene. This SOC depends on the orientation of the crown ring with respect to the Naph-π-plane. However, in the systems L1 and L2, the quenching is due to photoinduced electron transfer (PET) from nitrogen lone pair of the aza crown ring to naphthalene moiety and consequent exciplex formation. The results have been interpreted using the time-resolved emission studies of all the compounds in various solvents, their alkali metal ion complexes, and protonated ligands.     

Dynamics of self-focusing and self-phase modulation of elliptic Gaussian laser beam in a Kerr-medium

Using a direct variational technique involving elliptic Gaussian laser beam trial function, the combined effect of non-linearity and diffraction on wave propagation of optical beam in a homogeneous bulk Kerr-medium is presented. Particular emphasis is put on the variation of beam width and longitudinal phase delay with the distance of propagation. It is observed that no stationary self-trapping is possible. The regularized phase is also seen to be always negative.     

Syntheses and Characterization of Samarium and Erbium Borohydrido Complexes Supported by N‐Aryliminopyrrole Ligand

Reaction of potassium salt of N‐aryliminopyrrole ligand [2‐(2, 6‐iPr₂C₆H₃N=CH)–C₄H₃NK] ( 1 ) with samarium tris‐boro‐hydride [Sm(BH₄)₃(THF)₃] gave a samarium ate complex [η²‐{2‐(2, 6‐iPr₂C₆H₃N=CH)–C₄H₃N}₃Sm(η¹‐BH₄){K(THF)₆] ( 2 ); whereas similar treatment with erbium borohydride [Er(BH₄)₃(THF)₃] afforded the mono(iminopyrrolyl) complex [η²‐{2‐(2, 6‐iPr₂C₆H₃N=CH)–C₄H₃N}Er(η³‐BH₄)₂(THF)₂] ( 3 ). In the solid‐state structures, the samarium complex 2 shows a rarely observed η¹ and the erbium complex 3 shows a usual η³ coordination mode of the borohydrido ligand.     

Porous Anionic Co(II) Metal-Organic Framework,with a High Density of Amino Groups,as a Superior Luminescent Sensor for Turn-on Al(III) Detection

Accumulation of high concentrations of Al(III) in body has a direct impact on health and therefore, the trace detection of Al(III) has been a matter for substantial concern. An anionic metal organic framework ({[Me₂NH₂]_0.5[Co(DATRz)_0.5(NH₂BDC)] ⋅ xG}_n; 1 ; HDATRz=3,5-diamino-1,2,4-triazole, H₂NH₂-BDC=2-amino-1,4-benzenedicarboxylic acid, G=guest molecule) composed of two types of secondary building units (SBU) and channels of varying sizes was synthesized by employing a rational design mixed ligand synthesis approach. Free −NH₂ groups on both the ligands are immobilized onto the pore surface of the MOF which acts as a superior luminescent sensor for turn-on Al(III) detection. Furthermore, the large channels could allow the counter-ions to pass through and get exchanged to selectively detect Al(III) in presence of other seventeen metal ions with magnificent luminescence enhancement. The observed limit of detection is as low as 17.5 ppb, which is the lowest among the MOF-based sensors achieved so far. To make this detection approach simple, portable and economic, we demonstrate MOF filter paper test for real time naked eye observation.     

Assessing the Role of Digital Awareness in Promoting Polymer-Based Sustainability

The plastic waste crisis is a major environmental challenge facing the world today. The overuse and improper disposal of plastic materials have caused significant damage to the environment, affecting the health of both humans and animals. The adoption of sustainable alternatives to plastic, such as polymer-based materials, is crucial to addressing this issue. In the Indian context, polymer-based sustainability has created new growth potential for the packaging sector. This study has improved consumer behavior and raised income by gaining an understanding of and access to customers' digital awareness of polymer-based sustainability. In addition to its role in communication and attracting consumer attention, packaging must align with modern environmental standards for preservation methods to meet the growing consumer demand for eco-friendly products and environmentally conscious companies. In keeping with the objectives, this paper employs a method for analyzing current research on the influence of polymer-based sustainability esthetics on consumer behavior. The research design is quantitative. The model of the literature review is used to develop the structured questionnaire. The results show that digital awareness significantly influences consumer perceptions of polymer-based sustainability. The study recommends that manufacturers of polymer-based materials invest in digital awareness campaigns to increase consumer acceptance and promote sustainability.     

Eco-friendly synthesis of 1,8-naphthyridine 5-aryl-1,3,4-oxadiazole derivatives under solvent-free solid-state conditions and their antimicrobial activity

Research on Chemical Intermediates - A simple and highly efficient green synthetic procedure has been described for the construction of...     

Expedient synthesis of bisabolenol stink bug pheromones via stereodefined cyclohex-2-enones

We recently synthesized all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol, including three stink bug pheromones, via a rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones. However, yields of trans isomers were low, and scaling reactions using expensive catalysts were cumbersome. Now we describe a new synthesis of bisabolenol stink bug pheromones via (S)- and (R)-4-((R)-6-methylhept-5-en-2-yl)cyclohex-2-enones prepared by enantioselective Michael additions of methyl vinyl ketone to (S)- and (R)-citronellals and lithium hydroxide monohydrate-catalyzed stereoselective cyclizations of intermediate ketoaldehydes. Addition of methyllithium to these enones provided cis- and trans-1,10-bisaboladien-3-ols, which were separated by chromatography on silica and further converted to 10,11-epoxy-1-bisabolen-3-ols. Thus, we developed more convenient syntheses of pheromones of the rice stink bug, the harlequin bug, and brown marmorated stink bug.