Unravelling the intramolecular n → σ* interaction in ultra-electron deficient naphthalenediimides and their radical ions.

In this work, the role of non-covalent n → σ* intramolecular interactions in bestowing stabilization to exceptionally low-lying LUMO molecules of Naphthalenediimides (NDI) and their radical ions have been investigated utilizing different electronic structure calculation methods at the DFT level of theory and X-ray crystallography. We compared the effect of electron donating groups (EDGs) and electron-withdrawing groups (EWGs), , OMe and F, respectively, at the -positon of the phenylphosphonium groups integrated at the 2,6-positions of the NDI scaffold on the intramolecular P-O interactions and the evolving electronic effects. The natural bond orbital (NBO) analysis exhibited strong charge transfer from the imide O atoms of the NDI to the phosphorus atom of the phosphonium groups validating a donor-acceptor type of orbital interaction.

Oxidative Organic Transformations Photocatalyzed by NDI in Visible Light.

In this work, we report the synthesis and photocatalytic properties of -bis(-hexyl)-2-bromo-6-(-hexylamino)-1,4,5,8-naphthalenetetracarboxylic diimide photocatalyst, , in visible light. In the presence of air or oxidant, efficiently enables multiple photooxygenations of isoquinolines, thiocyanation of phenylimidazopyridines, functionalization of quinolinones by allowing regioselective installation of an SCN, SeCN, SPh, SePh, Cl, Br, or I group at the C-3 position, and isomerization of alkenes. Mechanistic investigations suggest an oxidative photoredox process for oxygenation and C-H functionalization, while isomerization is believed to proceed through a photosensitization pathway.

Noteworthy biocompatibility of effective microorganisms (EM) like microbial beneficial culture formulation with metal and metal oxide nanoparticles.

The present study evaluates the biocompatibility of silver and zinc oxide nanoparticles with various effective microorganisms (EM), like beneficial microbial formulations. The respective nanoparticle was synthesised by chemical reduction of metal precursor with reducer via simple route green technology principles. The synthesised nanoparticles were characterised by UV visible spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) studies, revealing highly stable, nanoscale particles with marked crystallinity.

Synthesis of a Highly Electron-Deficient, Water-Stable, Large Ionic Box: Multielectron Accumulation and Proton Conductivity.

π-acidic boxes exhibiting electron reservoir and proton conduction are unprecedented because of their instability in water. We present the synthesis of one of the strongest electron-deficient ionic boxes showing e uptake as well as proton conductivity. Two large anions fit in the box to form anion-π interactions and form infinite anion-solvent wires.

Facile synthesis of an ambient stable pyreno[4,5-]pyrrole monoanion and pyreno[4,5-:9,10-']dipyrrole dianion: from serendipity to design.

The stability of singly or multiply negatively charged π-conjugated organic compounds is greatly influenced by their electronic delocalization. Herein, we report a strategic methodology for isolation of a mysterious compound. The isolated compounds, a pyreno[4,5-]pyrrole monoanion and pyreno[4,5-:9,10-']dipyrrole dianion, were highly stable under ambient conditions due to high delocalization of the negative charge over multiple electron deficient C[triple bond, length as m-dash]N groups and pyrene π-scaffolds and allowed purification by column chromatography.

Photoredox halogenation of quinolones: the dual role of halo-fluorescein dyes.

An efficient C-3 halogenation of quinolin-4-ones is reported with halogenated fluorescein dyes which serve both as a halogen source and photocatalyst. This reaction shows broad substrate scope and gives good to excellent yields of C-3 brominated/iodinated quinolones with eosin Y/rose bengal in green light under ambient conditions. The mechanistic investigations suggest a radical pathway involving the oxidative dehalogenation of the dye in the presence of air.

Visible Light-Mediated Generation of δ,δ-Disubstituted -Quinone Methides: Construction of a Sterically Congested Quaternary Stereocenter.

An unprecedented visible light-assisted and zinc triflate-catalyzed construction of a diaryl-substituted quaternary stereocenter is reported. 2-(4-Hydroxyphenyl)-substituted aldehydes and ketones have been prepared in moderate to high yields via multicomponent reaction of acetylene, benzoquinone (BQ), and indole/aniline/thiol. The reaction is believed to proceed via generation of -quinone methide through a [2+2] cycloaddition-retroelectrocyclization of BQ and acetylene in blue light followed by a zinc triflate-catalyzed vinylogous Michael addition reaction with nucleophiles.

Synthesis of Novel Ciprofloxacin-Based Hybrid Molecules toward Potent Antimalarial Activity.

Antimalarial drug resistance is a serious obstacle in the persistent quest to eradicate malaria. There is a need for potent chemical agents that are able to act on drug-resistant populations at reasonable concentrations without any related toxicity to the host. By rational drug design, we envisaged to address this issue by generating a novel hybrid drug possessing two pharmacophores that can act on two unique and independent targets within the cell.

Synthesis of Stable, High-SOMO Zwitterionic Radicals: Enabling Intermolecular Electron Transfer between Naphthalenediimides.

Synthesis to enhance the electron donor ability of organic radicals has not been attempted due to reactivity challenges. Herein, naphthalenediimide-based (NDI) zwitterionic radicals are synthesized and isolated bestowing SOMO levels up to -4.04 eV.

Singlet oxygen mediated dual C-C and C-N bond cleavage in visible light.

A tandem cleavage of carbon-carbon and carbon-nitrogen bonds in imidazo[1,2-a]pyridines and imidazo[1,2-a]quinolines is reported in the presence of eosin Y and visible light. The ring opening occurs under ambient conditions through singlet oxygen insertion, bond cleavage and CO2 elimination, and produces N-(pyridin-2-yl) amides and N-(quinolin-2-yl) amides in high yields. The reaction shows good versatility, and does not require strong external oxidants and additives.

Doubly zwitterionic, di-reduced, highly electron-rich, air-stable naphthalenediimides: redox-switchable islands of aromatic-antiaromatic states.

The di-reduced state of the naphthalene moiety and its congeners have long captivated chemists as it is elusive to stabilize these intrinsically reactive electron-rich π-systems and for their emergent multifaceted properties. Herein we report the synthesis and isolation of two-electron (2e) reduced, highly electron-rich naphthalenediimides (NDIs). A doubly zwitterionic structure is observed for the first time in a naphthalene moiety and validated by single crystal X-ray crystallography and spectroscopic methods.

Synthesis and Isolation of a Stable Perylenediimide Radical Anion and Its Exceptionally Electron-Deficient Precursor.

The synthesis and isolation of an ambient stable perylenediimide radical anion is reported, and its precursor is established as one of the strongest electron acceptors. The radical anion shows absorption up to 1400 nm and is stable in mixed aqueous solution. Interestingly, the radical anion can organize two electron-deficient molecules over its surface to form a π-stacked array.

Ionic Assembly, Anion-π, Magnetic, and Electronic Attributes of Ambient Stable Naphthalenediimide Radical Ions.

Organic spin-based molecular materials are considered to be attractive for the generation of functional materials with emergent optoelectronic, magnetic, or magneto-conductive properties. However, the major limitations to the utilization of organic spin-based systems are their high reactivity, instability, and propensity for dimerization. Herein, we report the synthesis, characterization, and magnetic and electronic studies of three ambient stable radical ions (1 a , 1 b , and 1 c ).

Isolation of Tetracyano-Naphthalenediimide and Its Stable Planar Radical Anion.

Reported herein is the first isolation of tetracyano-naphthalenediimide [NDI(CN) ] and its radical anion, and structural elucidation through spectroscopic and X-ray diffraction studies. The radical anion shows remarkable stability and was purified by chromatography, which is unique for planar radical anions. The stability results from multiple hydrogen bonds to the counter ion and through an array of intramolecular noncovalent interactions.

Ambient Water-Stable Dianionic Electron Donors: Intramolecular Noncovalent Conduits Assist Charge Delocalization.

Electron-rich π-conjugated dianions are known to be ambient unstable and their stabilization in ambient water is yet to be realized. We report the first example of an exceptionally stable naphthalenediimide-based dianion in ambient and hot water, forming one of the most stable redox-active dianion. The half-life (t ) of dianion (1 a ) is more than four months in ambient water.

Correction: Elastic strain effects on catalysis of a PdCuSi metallic glass thin film.

Correction for 'Elastic strain effects on catalysis of a PdCuSi metallic glass thin film' by Yiyi Yang et al., Phys. Chem.

Synthesis of Octabromoperylene Dianhydride and Diimides: Evidence of Halogen Bonding and Semiconducting Properties.

A facile synthesis of octabromoperylene-3,4,9,10-tetracarboxylic dianhydride (Br8-PDA) (1), its diimides (Br8-PDIs) (2a-e), and bis-, tris-, and tetra-amino substituted diimides (5a-c) with six, five, and four remaining substitutable Br atoms, respectively, is reported. Octabromination results in facile chemical/electrochemical reduction, radical anion formation, and red-shifted optical properties. For the first time, diverse halogen-bonding interactions were identified in the PDA/PDI, which along with the attractive electronic features enhance the electron-transport characteristics compared to the di-/tetra-brominated PDIs (3/4).

Elastic strain effects on catalysis of a PdCuSi metallic glass thin film.

The influence of strain on catalytic activity has previously been examined directly by calculations and indirectly by experiments. The origin of the phenomenon has been attributed to strain-induced changes in the catalyst electronic structure. By employing a Pd-based metallic glass film capable of large elastic strains, we provide direct experimental evidence for catalytic activity being differently influenced by mechanically applied uniaxial tensile and compressive strains.

Extraordinary stability of naphthalenediimide radical ion and its ultra-electron-deficient precursor: strategic role of the phosphonium group.

Stabilization of radical ions and highly electron-deficient systems under ambient conditions is of great significance. A new design concept is presented that applies the multifaceted features of the phosphonium group to achieve isolation of (a) the first naphthalenediimide (NDI) radical ion [(1a•+)BPh4(–)] as single crystals and (b) an ultra-electron-deficient NDI [(1a(2+))2BF4(–)] having the lowest LUMO level recorded for an NDI, overwhelming the formative tetracyanoquinodimethane (TCNQ) molecule. Both 1a•+ and 1a(2+) exhibit unprecedented stability to normal workup procedures, chromatography, and anion metathesis in open air.

Dislocations in complex materials.

Deformation of metals and alloys by dislocations gliding between well-separated slip planes is a well-understood process, but most crystal structures do not possess such simple geometric arrangements. Examples are the Laves phases, the most common class of intermetallic compounds and exist with ordered cubic, hexagonal, and rhombohedral structures. These compounds are usually brittle at low temperatures, and transformation from one structure to another is slow.