0-D and 1-D Perovskite-like Hybrid Bismuth(III) Iodides.

Low-dimensional hybrid bismuth halide perovskites have recently emerged as a class of non-toxic alternative to lead perovskites with promising optoelectronic properties. Here, we report three hybrid bismuth(III)-iodides: 0-D (HDAC)BiI ⋅ 6HO (HDAC_Bi_I), 0-D (HDAF)BiI ⋅ 2I ⋅ 2I ⋅ 6HO (HDAF_Bi_I), and 1-D (HDAP)BiI (HDAP_Bi_I) (where HDAC=trans-1,4-diammoniumcyclohexane; HDAF=2,7-diammoniumfluorene and HDAP=1,5-diammoniumpentane). Their synthesis, single-crystal X-ray structures, and photophysical properties are reported.

[NH(CH)NH]SnX (X = Br, I): Dion-Jacobson type 2-D perovskites with short interlayer spacing.

Two-dimensional tin(II) halide perovskites stand as an environmentally benign alternative to Pb(II) halide perovskites. However, they are often challenging to make due to the oxidation of Sn(II) ion to more stable Sn(IV) ion. Here we report hybrid tin bromide and iodide perovskites: (1,4-BDA)Sn(IV)Br and (1,4-BDA)Sn(II)X (where X = Br, I; 1,4-BDA = 1,4-diammoniumbutane) with 0D and 2D structures, respectively.

Hybrid Iodide Perovskites of Divalent Alkaline Earth and Lanthanide Elements.

Hybrid halide perovskites AMX (A = ammonium cation, M = divalent cation, X = Cl, Br, I) have been extensively studied but have only previously been reported for the divalent carbon group elements Ge, Sn, and Pb. While they have displayed an impressive range of optoelectronic properties, the instability of Ge and Sn and the toxicity of Pb have stimulated significant interest in finding alternatives to these carbon group-based perovskites. Here, we describe the low-temperature solid-state synthesis of five new hybrid iodide perovskites centered around divalent alkaline earth and lanthanide elements, with the general formula AMI (A = methylammonium, MA; M = Sr, Sm, Eu, and A = formamidinium, FA; M = Sr, Eu).

Conformational Studies of β-Azapeptoid Foldamers: A New Class of Peptidomimetics with Confined Dihedrals.

Controlling amide bond geometries and the secondary structures of β-peptoids is a challenging task as they contain several rotatable single bonds in their backbone. Herein, we describe the synthesis and conformational properties of novel "β-azapeptoids" with confined dihedrals. We discuss how the acylhydrazide sidechains in these molecules enforce trans amide geometries (ω ~180°) via steric and stereoelectronic effects.

Elusive Double Perovskite Iodides: Structural, Optical, and Magnetic Properties.

Halide double perovskites [A M M X ] are an important class of materials that have garnered substantial interest as non-toxic alternatives to conventional lead iodide perovskites for optoelectronic applications. While numerous studies have examined chloride and bromide double perovskites, reports of iodide double perovskites are rare, and their definitive structural characterization has not been reported. Predictive models have aided us here in the synthesis and characterization of five iodide double perovskites of general formula Cs NaLnI (Ln=Ce, Nd, Gd, Tb, Dy).

Correction: Molybdenum chloride double perovskites: dimensionality control of optical and magnetic properties.

[This corrects the article DOI: 10.1039/D3SC00132F.].

Synergistic n → π* and n → π* interactions in C-terminal modified prolines: effect on Xaa-Pro / equilibrium.

Carbonyl-carbonyl (CO⋯CO) n → π* interaction often coexists with a hydrogen bond (HB) or another n → π* interaction. Although the interplay between HB and n → π* interaction was previously studied, there is no systematic investigation that shows a synergistic relationship of n → π* with another noncovalent interaction. Herein, we have studied a set of proline-diacylhydrazine (Pro-DAH) molecules and observed that increase in the strength of the n → π* interaction on their DAH side strengthened the n → π* interaction on the Pro side, which was experimentally determined by measuring the of the Xaa-Pro amide bond.

Molybdenum chloride double perovskites: dimensionality control of optical and magnetic properties.

Halide double perovskites are a promising class of semiconducting materials for applications in solar cells and other optoelectronic devices. Recently, there has been a surge of interest in these materials to study phenomena beyond optoelectronics, especially magnetism. Here, we report three new Mo (4d) based chloride double perovskites: a 3-D rock-salt ordered CsNaMoCl, a 1-D chain (MA)AgMoCl and a Dion-Jacobson type 2-D layered (1,4-BDA)AgMoCl (MA = methylammonium; 1,4-BDA = 1,4-butanediammonium).

Sidechain-Backbone Tetrel Bonding Interactions Provide a General Mechanism for trans-Peptoid Stabilization.

Cis-trans isomerization of amide bonds impedes de novo design of folded peptoids (poly-N-substituted glycines) with precise secondary structures and affects peptoid-biomolecule binding affinity. Herein, from X-ray, NMR and DFT studies of azapeptoids, we have discovered a tetrel bonding interaction that stabilizes trans-peptoids. We show that peptoids having α-heteroatoms and N-aryl groups in the sidechain adopt trans-amide geometries due to the presence of a n /π →σ* tetrel bonding interaction between the sidechain α-heteroatom lone pair (n ) or π-electrons (π ) and the σ* orbital of the backbone C -N bond.

Hybrid Layered Double Perovskite Halides of Transition Metals.

Hybrid layered double perovskite (HLDP) halides comprise hexacoordinated 1+ and 3+ metals in the octahedral sites within a perovskite layer and organic amine cations between the layers. Progress on such materials has hitherto been limited to compounds containing main group 3+ ions isoelectronic with Pb (such as Sb and Bi). Here, we report eight HLDP halides from the family, where = -phenylenediammonium (PPDA), 1,4-butanediammonium (1,4-BDA), or 1,3-propanediammonium (1,3-PDA); = Cu or Ag; = Ru or Mo; X = Cl or Br.

Chemical Control of Spin-Orbit Coupling and Charge Transfer in Vacancy-Ordered Ruthenium(IV) Halide Perovskites.

Vacancy-ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of Ru halides are presented; A RuCl and A RuBr , where A is K, NH , Rb or Cs. We show that the optical properties and spin-orbit coupling (SOC) behavior can be tuned through changing the A cation and the halide.

Structural Diversity and Magnetic Properties of Hybrid Ruthenium Halide Perovskites and Related Compounds.

There has been a great deal of recent interest in extended compounds containing Ru and Ru in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA RuX (X=Cl or Br), MA MRuX (M=Na, K or Ag; X=Cl or Br) and MA Ru X (X=Br) based upon the use of methylammonium (MA=CH NH ) on the perovskite A site.

1,3,5-Triphenylbenzene: a versatile photoluminescent chemo-sensor platform and supramolecular building block.

Fluorescence chemo-sensors for species of environmental and biological significance have emerged as a major research area in recent years. In this account, we describe fluorescence quenching as well as enhancement-based chemo-sensors obtained by employing -symmetric 1,3,5-triphenylbenzene (1,3,5-TPB) as the fluorescence signalling unit. 1,3,5-TPB is a thermally and photochemically stable fluorescent platform with π-electron-rich characteristics.

A covalently conjugated MoS/FeO magnetic nanocomposite as an efficient & reusable catalyst for H production.

Quick and easy recovery without the loss of the photocatalytic activity of the catalysing agent is an effective way to meet the challenges associated with the high cost of hazard-free hydrogen production. A '2D/0D' covalently conjugated nanocomposite of MoS/FeO has shown efficient catalyzing ability for five cycles of dye-sensitized H evolution.

Doping Phosphorene with Holes and Electrons through Molecular Charge Transfer.

An important aspect of phosphorene, the novel two-dimensional semiconductor, is whether holes and electrons can both be doped in this material. Some reports found that only electrons can be preferentially doped into phosphorene. There are some theoretical calculations showing charge-transfer interaction with both tetrathiafulvalene (TTF) and tetracyanoethylene (TCNE).

Triphenylbenzene Sensor for Selective Detection of Picric Acid.

A C -symmetric triphenylbenzene based photoluminescent compound, 1,3,5-tris(4'-(N-methylamino)phenyl) benzene ([NHMe]TAPB), has been synthesized by mono-N-methylation of 1,3,5-tris(4'-aminophenyl) benzene (TAPB) and structurally characterized. [NHMe]TAPB acts as a selective fluorescent sensor for picric acid (PA) with a detection limit as low as 2.25 ppm at a signal to noise ratio of 3.

Covalent Functionalization of Nanosheets of MoS and MoSe by Substituted Benzenes and Other Organic Molecules.

Covalent functionalization has been effectively employed to attach benzene functionalities to MoS and MoSe nanosheets by the reaction with para-substituted iodobenzenes bearing -OCH , -H, and -NO as the substituents, where the electron-donating and electron-withdrawing power of the para substituent varies significantly. The functionalization is based on the formation of a C-S or C-Se linkage at the expense of the C-I bond on reaction of the iodobenzene with electron-rich 1T-MoS or 1T-MoSe . The degree of functionalization is in the range 4-24 % range, the value increases with the electron-withdrawing power of the para substituent.

Three-Fold C 3-Symmetric Off-On Fluorescent Chemo-Sensors for Fluoride.

Three novel C 3-symmetric tris-salicylaldimine Schiff base based "off-on" fluorescence sensors have been designed and synthesized. The synthetic approach involves a simple imine bond (C = N) formation between 1,3,5-tris(4'-aminophenyl)benzene (TAPB) and 3,5-substituted salicylaldehydes. The presence of salicylaldehyde units on periphery of the tris-salicylaldimine Schiff bases masks the fluorescence of TAPB core.

Selective fluorescence sensing of polynitroaromatic explosives using triaminophenylbenzene scaffolds.

A supramolecular fluorophore, 1,3,5-tris(4'-aminophenyl)benzene (TAPB), selectively senses polynitroaromatic compounds (PNAC), viz. 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), picric acid (PA), m-dinitrobenzene (m-DNB) and p-dinitrobenzene (p-DNB) through donor-acceptor complexation. Steady-state and time resolved fluorescence measurements indicate predominantly static quenching of the TAPB fluorophore with TNT, DNT, m-DNB and p-DNB.