Combined effects of emitter-emitter and emitter-plasmonic surface separations dictate photoluminescence enhancement in a plasmonic field.

The brightness of an emitter can be enhanced by metal-enhanced fluorescence, wherein the excitonic dipole couples with the electromagnetic field of the surface plasmon. Herein, we experimentally map the landscape of photoluminescence enhancement (EF) of emitters in a plasmonic field as a function of the emitter-emitter separation, , and the emitter-plasmon distance, . We use Au nanoparticles overcoated with inert spacers as plasmonic systems and CdSe/ZnS quantum dots (QDs) as an emitter bearing opposite surface charges.

Modulating singlet fission through interchromophoric rotation.

Singlet fission (SF) is a spin-allowed, exciton-multiplying phenomenon that can be utilized to improve the efficiency of organic solar cells. It is well-understood that SF is sensitive to the local crystal morphology and an appropriately balanced coupling is essential to facilitate efficient SF. In this study, we show how the interchromophoric rotation selectively modulates the interaction between the monomer frontier molecular orbitals, promoting both fast and exothermal SF.

A mini-screen to identify the role of microRNAs in the Drosophila Insulin-Producing cells regulating lifespan.

Various genetic, molecular and environmental factors influence the lifespan of an organism, which includes the highly conserved insulin signaling pathway. In , Insulin-Producing cells (IPCs) present in the fly brain, analogous to vertebrate pancreas, control growth, metabolism and lifespan. Regulation of gene expression by microRNAs is strongly believed to be crucial in determining adult lifespan, however, no systematic approach has been conducted so far to study the role of microRNAs in the IPCs in the aging process.

Nutrient dependent aids in the survival of larvae during low food conditions.

Nutrition is one of the critical factors known to regulate the development and growth of organisms. Lack of nutrients affects the proper functioning and survival of organisms. However, fluctuation of the levels of nutrients is quite common in a natural environment, and organisms have evolved various molecular and physiological means by which they can survive such conditions.

NO Generation from the Cross-Talks between Ene-diol Antioxidants and Nitrite at Metal Sites.

The one-electron reduction of nitrite (NO) to nitric oxide (NO) and ene-diol oxidation are two important biochemical transformations. Employing mononuclear cobalt-nitrite complexes with Co and Co oxidation states, [()Co(nitrite)](ClO) () and [()Co(nitrite)](ClO) (), this report illustrates NO release coupled to stepwise oxidation of ene-diol antioxidants such as l-ascorbic acid (AH) and catechol. Analysis of the AH end-product reveals that the reaction with complex affords dehydroascorbic acid.

Modeling the Adsorption of Polycyclic Aromatic Hydrocarbons on Graphynes: An Improved Lennard-Jones Formulation.

Research on the development of theoretical methodologies for modeling noncovalent interactions governing the adsorption of polycyclic aromatic hydrocarbons (PAHs) on graphene and other two-dimensional materials is being intensely pursued in recent times. Highly accurate empirical potentials have emerged as a viable alternative to first-principles calculations for performing large-scale simulations. Herein, we report exploration of the potential energy surfaces for the adsorption of cata-condensed and peri-condensed PAHs on graphynes (GYs) using the improved Lennard-Jones (ILJ) potential.

Catechol oxidation promoted by bridging phenoxo moieties in a bis(μ-phenoxo)-bridged dicopper(ii) complex.

A dinuclear copper(ii) complex [Cu(papy)(CHOH)] has been synthesized by reaction of one equiv. of Cu(OAc)·2HO with one equiv. of the tetradentate tripodal ligand Hpapy [-(2-hydroxybenzyl)--(2-picolyl)glycine] and has been characterized by various spectroscopic techniques and its solid state structure has been confirmed by X-ray crystal structure analysis.

Cross-Talks Between Sulfane Sulfur and Thiol at a Zinc(II) Site.

Transformations of sulfane sulfur compounds (e. g. organic polysulfides (R-S -R, n>2) and elemental sulfur (S )) play pivotal roles in the biochemical landscape of sulfur, and thus supports signaling activities of H S.

InP-Bovine Serum Albumin Conjugates as Energy Transfer Probes.

The use of indium phosphide (InP) quantum dots (QDs) as biological fluorophores is limited by the low photoluminescence quantum yield (ϕ) and the lack of effective bioconjugation strategies. The former issue has been addressed by introducing a strain relaxing intermediate shell such as ZnSe, GaP etc. that significantly enhances the ϕ of InP.

Emulation of synaptic functions with low voltage organic memtransistor for hardware oriented neuromorphic computing.

Here, various synaptic functions and neural network simulation based pattern-recognition using novel, solution-processed organic memtransistors (memTs) with an unconventional redox-gating mechanism are demonstrated. Our synaptic memT device using conjugated polymer thin-film and redox-active solid electrolyte as the gate dielectric can be routinely operated at gate voltages (V) below - 1.5 V, subthreshold-swings (S) smaller than 120 mV/dec, and ON/OFF current ratio larger than 10.

Ligand-Induced Ground- and Excited-State Chirality in Silicon Nanoparticles: Surface Interactions Matter.

Silicon-based light-emitting materials have emerged as a favorable substitute to various organic and inorganic systems due to silicon's high natural abundance, low toxicity, and excellent biocompatibility. However, efforts on the design of free-standing silicon nanoparticles with chiral non-racemic absorption and emission attributes are rather scare. Herein, we unravel the structural requirements for ligand-induced chirality in silicon-based nanomaterials by functionalizing with D- and L-isomers of a bifunctional ligand, namely, tryptophan.

Manipulating the Self-Assembly of Phenyleneethynylenes under Vibrational Strong Coupling.

The chemical and physical properties of molecules and materials are known to be modified significantly under vibrational strong coupling (VSC). To gain insight into the effects of VSC on π-π interactions involved in molecular self-assembly, themselves sensitive to vacuum electromagnetic field fluctuations, the aggregation of two structural isomers (linear and V-shaped) of phenyleneethynylene under cooperative coupling was investigated. By coupling the aromatic C═C stretching band, the assembly of one of the molecules results in the formation of spheres as opposed to flakes under normal conditions.

An anisotropic dressed pairwise potential model for the adsorption of noble gases on boron nitride sheets.

Development of empirical potentials with accurate parameterization is indispensable while modeling large-scale systems. Herein, we report accurate parameterization of an anisotropic dressed pairwise potential model (PPM) for probing the adsorption of noble gases, He, Ne, Ar and Kr on boron nitride sheets. For the noble gas binding on BNH, we carried out a least-squares fit analysis of the dispersion and dispersionless contributions of the interaction potential separately.

O-Protected NH-free hydroxylamines: emerging electrophilic aminating reagents for organic synthesis.

In this highlight, O-protected NH-free hydroxylamine derivatives have been evaluated in the construction of nitrogen-enriched compounds, such as primary amines, amides, and N-heterocycles, with high regio-, chemo- and stereoselectivity in the unprotected form, showcasing the late-stage functionalization of natural products, drugs and functional molecules by biocatalysis, organocatalysis, and transition metal catalysis. The reactivity dichotomy among these N-O reagents has been explored based on SET and metal-nitrenoids.

Emergent chiroptical properties in supramolecular and plasmonic assemblies.

This tutorial provides a comprehensive description of the origin of chiroptical properties of supramolecular and plasmonic assemblies in the UV-visible region of the electromagnetic spectrum. The photophysical concepts essential for understanding chiroptical signatures are presented in the first section. Just as the oscillator strength (a positive quantity) is related to absorption, the rotational strength (either a positive or a negative quantity) defines the emergence of chiroptical signatures in molecular/plasmonic systems.

Surface hopping dynamics reveal ultrafast triplet generation promoted by S-T-T spin-vibronic coupling in 2-mercaptobenzothiazole.

We investigate the T formation upon populating the optically "bright" S in 2-mercaptobenzothiazole to interpret the underlying relaxation pathways associated with the experimental decay constants reported by D. Koyama and A. J.

Null Exciton-Coupled Chromophoric Dimer Exhibits Symmetry-Breaking Charge Separation.

A comprehensive understanding of the structure-property relationships in multichromophoric architectures has pushed the limits for developing robust photosynthetic mimics and molecular photovoltaics. The elusive phenomenon of null exciton splitting has gathered immense attention in recent years owing to the occurrence in unique chromophoric architectures and consequent emergent properties. Herein, we unveil the hitherto unobserved null exciton coupling assisted highly efficient photoinduced symmetry-breaking charge separation (SB-CS) in a Greek cross (+)-oriented spiro-conjugated perylenediimide dimer (Sp-PDI).

Seminar: Self-Assembly of Early Career Researchers toward Globally Accessible Nanoscience.

In 2020, many in-person scientific events were canceled due to the COVID-19 pandemic, creating a vacuum in networking and knowledge exchange between scientists. To fill this void in scientific communication, a group of early career nanocrystal enthusiasts launched the virtual seminar series, , in the summer of 2020. By the end of the year, the series had attracted over 850 participants from 46 countries.

Metal-free Transformations of Nitrogen-Oxyanions to Ammonia via Oxoammonium Salt.

Transformations of nitrogen-oxyanions (NO ) to ammonia impart pivotal roles in sustainable biogeochemical processes. While metal-mediated reductions of NO are relatively well known, this report illustrates proton-assisted transformations of NO anions in the presence of electron-rich aromatics such as 1,3,5-trimethoxybenzene (TMB-H, 1 a) leading to the formation of diaryl oxoammonium salt [(TMB) N =O][NO ] (2 a) via the intermediacy of nitrosonium cation (NO ). Detailed characterizations including UV/Vis, multinuclear NMR, FT-IR, HRMS, X-ray analyses on a set of closely related metastable diaryl oxoammonium [Ar N =O] species disclose unambiguous structural and spectroscopic signatures.

Electroforming-free nonvolatile resistive switching of redox-exfoliated MoSnanoflakes loaded polystyrene thin film with synaptic functionality.

Here, we report robust and highly reproducible nonvolatile resistive switching (RS) devices with artificial synaptic functionalities utilizing redox-exfoliated few-layered 2H-MoSnanoflakes. Advantageous polar solvent compatibility of 2D MoSfrom this method were utilized to fabricate thin film devices very easily and cost-effectively using polystyrene as matrix. Prominent RS property of polystyrene thin film devices with varying MoSconcentrations strongly favors electroforming-free operation.

Enhancement of Photoacoustic Signal Strength with Continuous Wave Optical Pre-Illumination: A Non-Invasive Technique.

Use of portable and affordable pulse light sources (light emitting diodes (LED) and laser diodes) for tissue illumination offers an opportunity to accelerate the clinical translation of photoacoustic imaging (PAI) technology. However, imaging depth in this case is limited because of low output (optical) power of these light sources. In this work, we developed a noninvasive technique for enhancing strength (amplitude) of photoacoustic (PA) signal.