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A new bio-active Schiff base was synthesized from cinnamaldehyde and aniline and the Zn(II), Ni(II) metal complexes have been synthesized and structurally characterized by micro-analytical, magnetic property, conductivity, mass spectra, FT-IR, Electronic absorption spectra, ¹H-NMR, and 13C-NMR spectral studies. The Physico-chemical and spectral data show that the complexes have the composition of 1:1 type of metal with a ligand. Its electronic absorption spectra and magnetic study proposed the tetrahedral geometry for Zn(II) complex and octahedral geometry for Ni(II) complex. It was further supported by the mass and IR spectra; the biological activities of Schiff base and their metal complexes were carried out by the Agar disc diffusion method. The results confirmed that the metal complexes enhanced the bio-potential activities than the free Schiff base. [ABSTRACT FROM AUTHOR]

A π-conjugated porous organic polymer (BCzBz) was fabricated employing N,N′-bicarbazole and benzothiadiazole as molecular building units exhibiting broad visible light absorption. The photostable, water-dispersible, and cytocompatible BCzBz was demonstrated as an efficient probe for intracellular reactive oxygen species generation under photoirradiation. [ABSTRACT FROM AUTHOR]

Frontispiece: Molecular Engineering Approaches Towards All-Organic White Light Emitting Materials Keywords: fluorescence; molecular engineering; noncovalent interactions; single molecules; white light emission EN fluorescence molecular engineering noncovalent interactions single molecules white light emission 1 1 1 05/06/20 20200504 NES 200504 B White light emitting (WLE) materials are of increasing interest b owing to their promising applications in artificial lighting, display devices, molecular sensors, and switches. Fluorescence, molecular engineering, noncovalent interactions, single molecules, white light emission. [Extracted from the article]

White light emitting (WLE) materials are of increasing interest owing to their promising applications in artificial lighting, display devices, molecular sensors, and switches. In this context, organic WLE materials cater to the interest of the scientific community owing to their promising features like color purity, long‐term stability, solution processability, cost‐effectiveness, and low toxicity. The typical method for the generation of white light is to combine three primary (red, green, and blue) or the two complementary (e.g., yellow and blue or red and cyan) emissive units covering the whole visible spectral window (400–800 nm). The judicious choice of molecular building blocks and connecting them through either strong covalent bonds or assembling through weak noncovalent interactions are the key to achieve enhanced emission spanning the entire visible region. In the present review article, molecular engineering approaches for the development of all‐organic WLE materials are analyzed in view of different photophysical processes like fluorescence resonance energy transfer (FRET), excited‐state intramolecular proton transfer (ESIPT), charge transfer (CT), monomer‐excimer emission, triplet‐state harvesting, etc. The key aspect of tuning the molecular fluorescence under the influence of pH, heat, and host–guest interactions is also discussed. The white light emission obtained from small organic molecules to supramolecular assemblies is presented, including polymers, micelles, and also employing covalent organic frameworks. The state‐of‐the‐art knowledge in the field of organic WLE materials, challenges, and future scope are delineated. [ABSTRACT FROM AUTHOR]

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 Å) and the π–π interaction between naphthalene and the rhodanine moiety (3.51 Å and 3.55 Å) 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 Å, 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Generating intense upconversion photoluminescence from a single‐phase nanocrystal is a fundamental problem. Herein, we report engineered NaYF4 nanocrystals capable of converting NIR (980 nm) excitation into sharp and diverse emissions in the UV‐Vis‐NIR regions, which is desirable for triggering multiple photoactive agents for enhanced photo‐theranostics. This unique emission profile is used for NIR‐induced photo‐theranostic applications by developing a nanoplatform with a white‐emitting NaYF4 (WEN) core, with comparable blue, green and red emissions, and a mesoporous silica shell decorated with two different photosensitizers (PSs), Rose Bengal (hydrophilic) and zinc(II)phthalocyanine (hydrophobic) to utilize green and red emissions, respectively. A chemical assay demonstrates efficient generation of 1O2 under NIR excitation by the dual PS nanoplatform compared to the conventional systems. Furthermore, NIR‐induced ROS generation leads to the enhanced photodynamic destruction of cancer cells (HeLa) in vitro. The white light from the nanoplatform is also utilized in cellular bioimaging. Unlike the previously reported upconversion probes, which required sophisticated imaging setups, the high intensity white light emission from this nanoplatform allows the probing of animal cells by a digital camera attached externally to an optical microscope. This is the first report on the theranostic application of a white‐light‐emitting photoluminescent nanomaterial. [ABSTRACT FROM AUTHOR]