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In an enduring quest to develop highly efficient display and lighting devices over the decades, semiconductor nanocrystals have recently emerged as favorable candidates. However, developing a prudent and viable methodology to fabricate high-quality semiconductor nanocrystals exhibiting tunable luminescence, including single-component white light emission, is challenging. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSeₓSy nanocrystals demonstrating high quantum yield using CdO, S powder, and Se powder as precursors. A phosphine-free route was adopted, employing paraffin oil as the reducing agent and solvent for the fabrication. The optical properties can be effectively tailored by controlling the reaction time and the Se/S molar ratio. The pristine CdSeₓSy nanocrystals exhibited a broad visible range emission from 400 to 750 nm. The CdSeₓSy nanocrystals (Se/S = 0.4) displayed white light emission with Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of (0.30, 0.31) and quantum yield of 50 ± 3%. Moreover, by manipulating the Se/S ratio effectively, the band-edge (∼400–450 nm) to trap-state (∼550–750 nm) emission was tuned, and the distinct shades of white light were obtained. The white light emission was retained in nanocrystals-embedded poly(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. Furthermore, white light emission characteristics from CdSeₓSy nanocrystals (Se/S = 0.4), PMMA thin film, and thin film coated white light emitting devices were found to be similar even after months of fabrication, indicating the high stability of the nanocrystals and sustainability of the materials derived from nanocrystals. The one-pot, low-cost fabrication route demonstrated in the present study offers the promising scope of white light emitting CdSeₓSy nanocrystals in solid-state display applications.

The Main Boundary Thrust (MBT) Zone in the Darjeeling foothills, Eastern Himalaya exhibits northerly dipping fault splays, named here as MBT-1 and MBT-2, with Proterozoic Daling Group in the MBT-1 hanging wall, Upper Paleozoic Gondwana rocks between the MBT-1 and the MBT-2, and Neogene Siwalik Group in the footwall of the MBT-2. On the basis of reduced stress tensors from fault-slip analysis and their grouping relative to different stratigraphic units in the MBT zone that crops out over a strike length of ∼20 km, the following successive stress regimes have been interpreted. The earliest brittle deformation recorded only in the basal part of the Gondwana succession was controlled by a pre-Himalayan NW-SE extensional regime. The Himalayan deformation under sustained N-S compressive regime developed in three stages: (a) thrust displacement along the MBT-1, juxtaposing folded Daling rocks against the Lower Gondwana rocks; (b) tilting and fracturing of Lower Gondwana succession and thrust transport over the Siwalik rocks along the MBT-2; (c) strike-slip regime with NW- and NE-trending faults affecting both the Lower Gondwana and Siwalik strata, developed possibly due to increased tectonic loading. The tensor solutions under N-S compressional regime are consistent with the modern plate convergence, supporting a foreland propagating thrust system in the Eastern Himalaya. In addition, an E-W extensional regime led to apparent orogen-parallel extension.

A heptazine-based microporous polymeric network, HMP-TAPA was synthesised by direct coupling of trichloroheptazine and tris(4-aminophenyl)amine (TAPA). A high surface area of 424 m2 /g was achieved, which is the highest surface area among heptazine-based polymeric networks (HMPs). The tailored electron-donor and -acceptor units in HMP-TAPA give broad visible-light absorption. HMP-TAPA was employed as metal-free photocatalyst for oxidative coupling of amines to imines under visible light irradiation with 98 % selectivity. Furthermore, the surface basicity of HMP-TAPA was used to achieve metal-free heterogeneous base catalysis for Knoevenagel condensation under base-free conditions with >99 % conversion. In addition, HMP-TAPA showed extreme robustness over a wide pH range (1-14). The versatility and flexibility of the current material design is beneficial for understanding its photoactivity and surface basicity so as to design dual active (photo)catalyst materials for specific applications.

We fabricated an inorganic–organic hybrid upconversion nanoprobe for the ratiometric detection of aliphatic biogenic amines in water. The hybrid nanoprobe comprises a thiophene-based acceptor–π-donor–π-acceptor organic fluorescent dye, TDPM, and near-infrared light-absorbing upconversion nanoparticles (UCNPs). The organic dye was loaded into a mesoporous silica-coated UCNP (UCNP@mSiO2) matrix to circumvent the issues of water insolubility and higher energy excitation. Yb3+ and Tm3+-doped UCNPs exhibited dual emission bands at 475 and 645 nm upon excitation with a 980 nm laser. The significant spectral overlap between the absorption and the emission bands of TDPM and UCNPs, respectively, at 475 nm led to resonance energy transfer (RET) from the UCNPs to TDPM resulting in the quenching of the UCNP emission. In contrast, ‘turn-on’ emission was noticeable with the addition of aliphatic biogenic amines due to an inhibition of the RET. The emission at 645 nm remained unaffected during the energy transfer process making the hybrid probe a versatile platform for the ratiometric detection of different aliphatic biogenic amines. Furthermore, we explored the sensing of aliphatic biogenic amines in adulterated milk and rotten fish. The unique material attributes demonstrated in the current study hold promise for further development of real-time sensors and switches based on hybrid upconversion nanoprobes.

Covalent organic frameworks (COFs) having layered architecture with open nanochannels and high specific surface area are promising candidates for energy storage. However, the low electrical conductivity of two-dimensional COFs often limits their scope in energy storage applications. The conductivity of COFs can be enhanced through post-synthetic modification with conducting polymers. Herein, we developed polyaniline (PANI) modified triazine-based COFs via in situ polymerization of aniline within the porous frameworks. The composite materials showed high conductivity of 1.4-1.9×10-2 S cm-1 at room temperature with a 20-fold enhancement of the specific capacitance than the pristine frameworks. The fabricated supercapacitor exhibited a high energy density of 24.4 W h kg-1 and a power density of 200 W kg-1 at 0.5 A g-1 current density. Moreover, the device fabricated using the conducting polymer-triazine COF composite could light up a green light-emitting diode for 1 min after being charged for 10 s.

The current study demonstrates a simple and economical synthetic approach for the development of a multifunctional Schiff base compound (NRSB) through the condensation reaction between 2-hydroxynaphthaldehyde and a five-membered heterocycle 3-aminorhodanine. The rhodanine unit was chosen due to the presence of an active electron-deficient carbonyl group. A facile chemical transformation from the closed to the open form was noticeable for rhodanine derivatives in the presence of a suitable nucleophile or an electron-rich system. Such a unique feature was invoked to develop a versatile molecular platform for the colorimetric sensing of methanol and the fluorometric detection of Al3+ ions. The nucleophilic attack by methanol on NRSB led to the formation of an open-ring compound, NRSB-O, with a distinct change in color from colorless to yellow. NRSB showed noticeable sensitivity towards methanol and the detection limit was found to be 0.43 wt%. The methanol-induced chemical transformation from NRSB to NRSB-O was probed through X-ray diffraction studies. The strong CH–π interaction between the methylene protons of the rhodanine unit and the π-electron cloud of the naphthalene unit (3.03 A) and the π–π interaction between naphthalene and the rhodanine moiety (3.51 A and 3.55 A) lead to a two-dimensional (2D) supramolecular structure in the NRSB crystal. NRSB-O possesses strong CH–π interactions between molecules with an intermolecular distance of 2.49 A, leading to 2D-supramolecular self-assembly. The crystal structure revealed the scope of the chelation of NRSB-O with metal ions due to the presence of different N, O, and S donor centers. Interestingly, NRSB-O exhibited a turn-on fluorescence response specifically towards Al3+ through the chelation-enhanced fluorescence (CHEF) mechanism over other competitive metal ions. The turn ‘on–off’ fluorescence switching was demonstrated for multiple cycles through the alternative addition of Al3+ and EDTA. The low-cost, simple design strategy of NRSB and NRSB-O as delineated in the current study would contribute to further development of task-specific molecular sensors and switches.

The excited-state intramolecular proton transfer (ESIPT)-based molecular probes have drawn significant attention owing to their environment-sensitive fluorescence properties, large Stokes shift, and emerged as building blocks for the development of molecular sensors and switches. However, most of the ESIPT-based fluorophores exhibit weak emission in the solid state limiting the scope of real-time applications. Addressing such issues, herein, we presented a C

A novel approach for the fabrication of a solution processable conjugated porous organic polymer (CzBDP) involving a flexible core composed of carbazole and boron dipyrromethene was developed. The red emitting soluble polymer was found to be an excellent probe for the generation of both singlet oxygen and superoxide anion radicals under visible light irradiation.

The intramolecular charge transfer-driven emission properties of T and V-shaped donor-acceptor-donor molecules involving a new acceptor core of pyridoquinoxaline were demonstrated. The T-shaped molecule exhibits a large Stokes shift, red emission in the solid state and remarkable viscosity and temperature-dependent tunable fluorescence including a thermally-induced single-component near white-light emission.

The present study demonstrates the tuning of iconic optical features of pyrene through its judicious assembly with a C3-symmetric triaminoguanidinium ion, leading to the development of a unique multifunctional luminescent material PYTG. By fine tuning the concentration and the external stimuli, such as temperature, the addition of analytes led to a dramatic change in the fluorescence of PYTG, providing an excellent platform for the exploration of the dynamic and static excimer formation. Recently, white-light-emitting molecular probes have received considerable attention from the scientific community due to their great potentials in display devices. Tripodal PYTG was employed as a pure white-light emitter consisting of blue emission from monomers and orange emission from excimers both in solution and thin film with Commission Internationale de l’Eclairage (CIE) coordinates of (0.33, 0.34) and (0.33, 0.38), respectively. The formation of a dynamic excimer along with monomer fluorescence at higher concentrations of PYTG led to tunable emission. Additionally, the rich electronic properties of PYTG allowed efficient detection of trivalent metal ions by turn-on fluorescence and colorimetric sensing of fluoride ions. PYTG selectively detected Fe3+ and Al3+ with nanomolar sensitivity in a semi-aqueous solution via a chelation-enhanced fluorescence response in the orange-red region (λem = 588 nm) by static excimer formation. The ‘on–off’ fluorescence switching by the consecutive addition of trivalent cations and a chelating ligand EDTA makes PYTG a promising fluorescent molecular switch. A simple and cost-effective strategy, leading to the development of a versatile fluorescent probe and an in-depth exploration of the structure–property relationship as delineated in the present manuscript, will pave the way for the emergence of novel task-specific molecular optical materials.

A simple and cost-effective methodology employing environmentally benign substances for the fabrication of white-light emitting materials is important for practical applications in the field of lighting and display devices. Designing purely organic-based white-light-emitting systems with high quantum efficiency in aqueous media is an unmet challenge. With this objective, a new class of pyridoindole-based hydrophobic fluorophore 6,7,8,9-tetrapropylpyrido[1,2-a]indole-10-carbaldehye (TPIC) was introduced. A strategy of self-assembly using nonionic surfactants was employed to enhance the fluorescence of TPIC in an aqueous medium and was exploited as energy donor. The steady-state and time-resolved emission spectra analysis revealed the micelle-mediated energy transfer from TPIC to Nile red (energy acceptor) leading to tunable fluorescence along with white-light emission. The white-light emitting aqueous solution was obtained with the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.33, 0.36) and significantly high quantum yield of 37 %. Solid-state white-light emission was achieved retaining the assembly of fluorophores in the form of a gel having the high quantum efficiency of 33 % with CIE coordinates of (0.32, 0.36); close to that of pure white light. The bright white luminescence of the inscription prepared using white-light emitting gel on a solid substrate offers promising applications for full-color flat panel displays.

The origin of reddening of granitoid is controversial. Red granitoids, occurring spatially with grey granitoids with a thin transitional zone is a volumetrically significant litho-type in the Bundelkhand Craton, north central India. Using detailed petrography and microstructure study, and phase compositions and elemental X-ray maps, we demonstrate for the first time that pervasive infiltration of Fe-Mg-Na-K-rich fluid caused re-equilibration of ~2.5 Ga grey monzogranite during both brittle and ductile deformation in the craton. The reddening of granitoid is attributed to replacement and precipitation of tiny Fe-rich particles in porous feldspars by the high temperature Fe-Mg-Na-K-rich fluid (~950°C), plausibly from crust–mantle depths. The Fe-Mg-Na-K-rich fluid with high to moderately high FeO (≤27 wt%), MgO (≤19 wt%), Al2O3 (≤20 wt%), Na2O (

Taking C-phenylresorcin[4]arene (RN4) as a model building block, we fabricated a series of porous organic polymers (POPs: RN4-OH, RN4-Az-OH, and RN4-F) where the surface area was enhanced up to ~8 folds (1229 m2 g-1) than that of the pristine cavitand (156 m2 g-1). The advantage of connecting the 0D porous cavitands was demonstrated through three environmentally relevant applications, namely, catalytic conversion of CO2 to value-added products, selective gas (CO2, H2) uptake, and the charge-specific size-selective separation of organic micropollutants from water. In all the cases, RN4-derived POPs have outperformed the pristine 0D porous macrocyclic cavitand.

A new core of [1,2,5]-thiadiazolo-[3,4-c]-pyridine was employed for the fabrication of microporous organic polymers exhibiting a very high CO2 uptake of 5.8 mmol g−1 (25.5 wt%) at 273 K and 1 bar. The presence of CO2-philic active sites and microporosity confer the high uptake and superior selectivity (61) towards CO2 over N2.

A series of porous organic polymers (POPs) were fabricated based on a boron dipyrromethene (BODIPY) core. The variation of the substituents in the BODIPY core and the fine-tuning of the Sonogashira polycondenzation reaction with 1,3,5-triethynylbenzene led to the formation of POPs with a wide range of surface area and porosity. A 10-fold increase in surface area from 73 m2 g–1 in BDT1a polymer to 1010 m2 g–1 in BDT3 was obtained. Simultaneously, the porosity was changed from mesoporous to ultramicroporous. The surface area of BDT3 turned out to be the highest reported so far for BODIPY-based POPs. Molecular dynamics simulation coupled with Grand Canonical Monte Carlo simulations revealed the effect of substituents alkyl groups and rigidity of the core structures on the surface properties of the POPs. Detailed gas adsorption studies of the polymers revealed a high uptake of CO2 and H2. The highest uptake capacity of 16.5 wt % for CO2 at 273 K and 2.2 wt % for H2 at 77 K was observed for BDT3 at 1 bar press...

A novel class of pyrene-based conjugated porous organic polymers having an N-containing network was developed by employing Buchwald–Hartwig coupling for supercapacitor energy storage. The pristine polymer was found to exhibit a specific capacitance of 456 F g−1 at 0.5 A g−1 current density with excellent long-term cyclic stability.

Schiff base condensation and C–C coupling between a biologically important heterocycle pyrido[1,2-a]indole (PI) and aggregation induced emission active tetraphenylethylene (TE) led to the formation of weakly fluorescent PITE1 and strongly fluorescent PITE2, respectively. The photophysical phenomenon was rationalized by crystal structure analysis; PITE2 was found to exhibit strong fluorescence in solution, nanoparticles and solid state.

A versatile fluorescent probe, PITE, based on alkyl-substituted pyridoindole (PI) and tetraphenylethylene (TE), which exhibits facile pH-induced fluorescence switching in solution, as nanoparticles, and in the solid state, is presented. Strong fluorescence in the solid state, as well as in solution and the aggregated state, allow sensing of toxic acid vapors. Fluorescence "off-on" switching of PITE through exposure to trifluoroacetic acid and triethylamine vapor is visualized by the naked eye. A unified picture of the switchable fluorescence of PITE is obtained by comprehensive spectroscopic investigations coupled with quantum mechanical calculations. Strong fluorescence, a large Stokes shift, high photostability, and biocompatibility of PITE make it a viable probe for subcellular imaging. Extensive fluorescence microscopic studies by employing organisms including lower and higher eukaryotes reveal specific localization of PITE to lipid droplets (LDs). LDs are dynamic subcellular organelles linked to various physiological processes and human diseases. Hence, the specific detection of LDs in diverse organisms is important to biomedical research and healthcare. Isolation of LDs and subsequent colocalization studies ascertain selective targeting of LDs by the easily affordable, lipophilic bioprobe, PITE. Thus, PITE is a promising multifunctional probe for chemosensing and the selective tracking of LDs.

A tetraphenylcyclopentadiene based multifunctional, solution processable, fluorescent, ultramicroporous polymer exhibiting high hydrogen uptake was employed for encapsulation of dyes to obtain enhanced white light emission in solution, nanoparticles, gel and transparent thin film. Hybrid nanoparticles showed a quantum yield of 35% with a high color rendering index.

Conjugated polymer nanoparticles based on poly[9,9-bis(2-ethylhexyl)fluorene] and poly[N-(2,4,6-trimethylphenyl)-N,N-diphenylamine)-4,4'-diyl] are fabricated using anionic surfactant sodium dodecylsulphate in water by miniemulsion technique. Average diameters of polyfluorene and polytriarylamine nanoparticles range from 70 to 100 and 100 to 140 nm, respectively. The surface of the nanoparticles is decorated with triplet emitting dye, tris(2,2'-bipyridyl)ruthenium(II) chloride. Intriguing photophysics of aqueous dispersions of these hybrid nanoparticles is investigated. Nearly 50% quenching of fluorescence is observed in the case of dye-coated polyfluorene nanoparticles; excitation energy transfer is found to be the dominant quenching mechanism. On the other hand, nearly complete quenching of emission is noticed in polytriarylamine nanoparticle-dye hybrids. It is proposed that the excited state electron transfer from the electron-rich polytriarylamine donor polymer to Ru complex leads to the complete quenching of emission of polytriarylamine nanoparticles. The current study offers promising avenues for developing aqueous solution processed-electroluminescent devices involving a conjugated polymer nanoparticle host and Ru or Ir-based triplet emitting dye as the guest.