Search results for "Heteroatom"

Neutral nido-heteroboranes with non ionisable hydrogen as arenes in coordination

2003

Designed ligands have been synthesised to produce the first arene-like metallacarborane. For arene-like coordination the number of electronegative elements on the coordinating site must be kept to a minimum. Choosing ligands with bulky substituents on the heteroatom allows easy rearrangement and arene-like coordination. This is more hampered the higher the number of hetereoatoms to be re-located.

N-Heterocyclic Carbenes with Inorganic Backbones:  Electronic Structures and Ligand Properties

2008

The electronic structures of known N-heterocyclic carbenes (NHCs) with boron, nitrogen, and phosphorus backbones are examined using quantum chemical methods and compared to the experimental results and to the computational data obtained for a classical carbon analogue, imidazol-2-ylidene. The sigma-donor and pi-acceptor abilities of the studied NHCs in selected transition-metal complexes are evaluated using a variety of approaches such as energy and charge decomposition analysis, as well as calculated acidity constants and carbonyl stretching frequencies. The study shows that the introduction of selected heteroatoms into the NHC backbone generally leads to stronger metal-carbene bonds and t…

The Synthesis of Spherical Mesoporous Molecular Sieves MCM-48 with Heteroatoms Incorporated into the Silica Framework

1999

Ultra-thin film sensors based on porphyrin-5-ylphosphonate diesters for selective and sensitive dual-channel optical detection of mercury(II) ions

2020

International audience; Reusable dual-channel optical sensors for Hg2+ ions were prepared by Langmuir-Schaefer (LS) method from amphiphilic (trans-A2)BC-type porphyrins functionalized at meso-positions of the tetrapyrrolic macrocycle by sterically demanding diethoxyphosphoryl and mesityl groups as well as electron donating RO, RS or RNH substituents (R = n-C8H17). These three novel amphiphilic porphyrin derivatives were synthesized in good yields and their floating films at the air⎯water interface were investigated. In these monolayers, porphyrin molecules display a slipped stack-of-card orientation, but their strong π stacking is prohibited by bulky diethoxyphosphoryl and mesityl groups. T…

Heteroatom Effect on Star-Shaped Hole-Transporting Materials for Perovskite Solar Cells

2018

Dimensional Confinement in Carbon-based Structures - From 3D to 1D

2017

We present an overview of charge transport in selected one-, two- and three-dimensional carbon-based materials with exciting properties. The systems are atomically defined bottom-up synthesized graphene nanoribbons, doped graphene and turbostratic graphene micro-disks, where up to 100 graphene layers are rotationally stacked. For turbostratic graphene we show how this system lends itself to spintronic applications. This follows from the inner graphene layers where charge carriers are protected and thus highly mobile. Doped graphene and graphene nanoribbons offer the possibility to tailor the electronic properties of graphene either by introducing heteroatoms or by confining the system geome…

O-Doped Nanographenes: A Pyrano/Pyrylium Route Towards Semiconducting Cationic Mixed-Valence Complexes

2020

Herein we report an efficient synthesis to prepare O‐doped nanographenes, which derive from the longitudinally and latitudinally p‐extension of pyrene. The derivatives are highly fluorescent and feature low‐oxidation potentials. Exploiting electrooxidation, crystals of cationic mixed valence (MV) complexes were grown in which the organic salts organize into face‐to‐face p‐ p stacks, a favorable solid‐state arrangement for organic electronics. Variable‐temperature EPR measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar p‐stacking architectures. Electric measurements of single crystals of the MV salts exhibited a semiconduct…

Structure-Guided, Single-Point Modifications in the Phosphinic Dipeptide Structure Yield Highly Potent and Selective Inhibitors of Neutral Aminopepti…

2014

Seven crystal structures of alanyl aminopeptidase from Neisseria meningitides (the etiological agent of meningitis, NmAPN) complexed with organophosphorus compounds were resolved to determine the optimal inhibitor–enzyme interactions. The enantiomeric phosphonic acid analogs of Leu and hPhe, which correspond to the P1 amino acid residues of well-processed substrates, were used to assess the impact of the absolute configuration and the stereospecific hydrogen bond network formed between the aminophosphonate polar head and the active site residues on the binding affinity. For the hPhe analog, an imperfect stereochemical complementarity could be overcome by incorporating an appropriate P1 side…

Bicyclic 5-5 Systems with One Ring Junction Nitrogen Atom: One Extra Heteroatom 1:0

1996

Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems

2016

The application of organoboron compounds as light-absorbing or light-emitting species in areas as relevant as organic electronics or biomedicine has motivated the search for new materials which contribute to the progress of those applications. This article reports the synthesis of four-coordinate boron complexes based on the unexplored 7-(azaheteroaryl)indole ligands. An easy synthetic approach has enabled the fine-tuning of the electronic structure of the organoboron species by modifying a heteroaromatic component in the conjugated system. Furthermore, a comprehensive characterization by X-ray diffraction, absorption and emission spectroscopy, both in solution and in the solid state, cycli…