Electronically Induced Steric Clash: Synthesis of NMe2-Modified β-Diketiminate-Supported Boron Difluoride Compounds

2020 ◽  
Vol 73 (12) ◽  
pp. 1219
Author(s):  
Balasubramanian Murugesapandian ◽  
Rakesh Ganguly ◽  
Peter T. K. Lee ◽  
Milena Petković ◽  
Jason A. C. Clyburne ◽  
...  
Keyword(s):  
Solid State ◽  
Lone Pair ◽  
Structural Features ◽  
Electron Delocalization ◽  
Central Ring ◽  
Steric Clash ◽  
Boron Difluoride ◽  
Theoretical Analyses

We report on the synthesis and structural features of NMe2-modified β-diketiminate-supported boron difluoride compounds (LArBF2: LAr=[HC(NAr)2(CNMe2)2]–; LPh: Ar=Ph; LTol: Ar=p-tolyl; LXyl: Ar=m-xylyl). The title compounds were prepared in moderate yields (~65%) by insitu deprotonation of the corresponding ligands LArH using KH, followed by the addition of BF3OEt2. According to solid-state and theoretical analyses of the BF2 compounds, the lone pair at each NMe2 group is involved in electron delocalization within the central BC3N2 ring. As a result, the N-aryl substituents sterically clash with the NMe2 groups, causing this central ring to pucker. Several attempts were made to prepare heavy analogues (e.g. LArBX2, X=Cl, Br, I) but only unidentifiable product mixtures were observed. It appears that the observed steric clash between the N-aryl substituents and the NMe2 groups prevented the formation of these heavy analogues.

A new one-dimensional strontium vanadium tellurite, Sr7V4Te12O41

2016 ◽  
Vol 72 (8) ◽  
pp. 647-651 ◽  
Author(s):  
Sun Woo Kim ◽  
Thomas J. Emge ◽  
Martha Greenblatt
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Lone Pair ◽  
Structural Features ◽  
One Dimensional ◽  
Axis Direction ◽  
Lone Pair Electrons

Vanadium tellurites display a rich structural chemistry with interesting physical properties, such as second harmonic generation (SHG). Tellurites,i.e.Te4+Ox, are often observed in unusual structures and form various structural motifs, including isolated clusters, chains, layers, and three-dimensional networks. Similarly, vanadates,i.e.V5+Ox, show rich structural features, such as VO4tetrahedra, VO5square pyramids or trigonal bipyramids, and VO6octahedra. Strontium vanadium tellurite, Sr7V4Te12O41, was obtained from the melt of the solid-state reaction of SrTeO4and VO2in a sealed quartz tube as it cooled from 973 K. The crystal structure exhibits a one-dimensional latticework along theaaxis comprised of paired Sr3Te3Oxunits, namely Sr6Te6O2x+1, with corner-shared TeO4polyhedra – and specifically the Te lone-pair electrons – facing outward in thebcplane. The Sr6Te6O2x+1latticework is helical and is layered in theb-axis direction against sheets of corner-shared VO4tetrahedra, and is linked in thec-axis directionviaindividual corner-shared SrO8square prisms.

Complexation of 7-azaindole by the methylmercury(II) cation

1992 ◽  
Vol 70 (12) ◽  
pp. 2914-2921 ◽  
Author(s):  
Nathalie Dufour ◽  
Anne-Marie Lebuis ◽  
Marie-Claude Corbeil ◽  
André L. Beauchamp ◽  
Pascal Dufour ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Pyridine Ring ◽  
Coordination Mode ◽  
Pyrrole Ring ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Major Influence ◽  
Large Displacements ◽  
Dmso Solution

Complexes of the types [CH3Hg(aza)], [CH3Hg(Haza)]X, and [(CH3Hg)2(aza)]X are obtained by reacting CH3HgOH and/or CH3HgX (X = NO3, ClO4) with 7-azaindole (Haza). The weakly acidic N1-H proton on the pyrrole ring is displaced by the hydroxide, whereas the perchlorate and nitrate salts lead to CH3Hg+ coordination to the N7 lone pair on the pyridine ring. Detailed analysis of the infrared spectra of the complexes and their N-deuterated derivatives provides diagnostic regions for eventual prediction of the coordination mode in other systems. All compounds are characterized by means of 1H, 13C, and 199Hg NMR spectra in DMSO solution and solid-state CP-MAS 13C spectra. Comparison of the solution and solid-state 13C spectra show that the species present in the solids remain undissociated in DMSO. Each type of complex can be identified from a characteristic pattern of large displacements of the ligand 13C signals. The 1H spectra are less informative because substitution of the N1-H proton by CH3Hg+ induces only minor shifts. Metal solvation appears to have a major influence on the 13C and 199Hg chemical shifts of the CH3Hg+ groups.

Equilibrium and Kinetic Properties of Minerals

1998 ◽  
Vol 62 (5) ◽  
pp. 581-583
Author(s):  
Simon A. T. Redfern
Keyword(s):  
Solid State ◽  
Statistical Mechanics ◽  
Structural Features ◽  
Atomic Scale ◽  
Kinetic Properties ◽  
Computational Power ◽  
Equilibrium Thermodynamics ◽  
Bulk Properties ◽  
Scale Characteristics ◽  
Number Of Publications

How can the equilibrium and non-equilibrium thermodynamics of minerals be understood from their atomic-scale structural features? How can they be predicted, simply from models for the forces between atoms? Advances in analytical theory, statistical mechanics, experimental solid-state science, computational power, and the sophistication of a mineralogical approach that brings all of these together, means that these questions, once imponderable, are now realistically tractable. These questions have been exercising the minds of mineralogists over the last decade or so, and have motivated many developments in the science. Acting as way-markers along the path, there are a number of publications which have followed from meetings where these questions have been addressed. It is now twelve years since the publication of Microscopic to Macroscopic, an edition of Reviews in Mineralogy (Kieffer and Navrotsky, 1985) that sought to identify the fundamental controls on the bulk properties of minerals in terms of their atomic-scale characteristics.

scholarly journals Redox-State Dependent Spectroscopic Properties of Porous Organic Polymers Containing Furan, Thiophene, and Selenophene

2017 ◽  
Vol 70 (11) ◽  
pp. 1227 ◽  
Author(s):  
Carol Hua ◽  
Stone Woo ◽  
Aditya Rawal ◽  
Floriana Tuna ◽  
James M. Hook ◽  
...  
Keyword(s):  
Solid State ◽  
Redox State ◽  
Spectroscopic Properties ◽  
Structural Features ◽  
Organic Polymers ◽  
Stimuli Responsive ◽  
Porous Organic Polymers ◽  
Paramagnetic Resonance ◽  
Responsive Materials ◽  
State Dependent

A series of electroactive triarylamine porous organic polymers (POPs) with furan, thiophene, and selenophene (POP-O, POP-S, and POP-Se) linkers have been synthesised and their electronic and spectroscopic properties investigated as a function of redox state. Solid state NMR provided insight into the structural features of the POPs, while in situ solid state Vis-NIR and electron paramagnetic resonance spectroelectrochemistry showed that the distinct redox states in POP-S could be reversibly accessed. The development of redox-active porous organic polymers with heterocyclic linkers affords their potential application as stimuli responsive materials in gas storage, catalysis, and as electrochromic materials.

Anomalous stabilizing and destabilizing effects in some cyclic π-electron systems

1993 ◽  
Vol 71 (8) ◽  
pp. 1123-1127 ◽  
Author(s):  
Peter Politzer ◽  
M. Edward Grice ◽  
Jane S. Murray ◽  
Jorge M. Seminario
Keyword(s):  
Ab Initio ◽  
Lone Pair ◽  
Electrostatic Potentials ◽  
Electron Delocalization ◽  
Isodesmic Reaction ◽  
Computational Studies ◽  
Electron Systems ◽  
Molecular Electrostatic Potentials ◽  
Lone Pairs

Ab initio computational studies have been carried out for three molecules that are commonly classed as antiaromatic: cyclobutadiene (1), 1,3-diazacyclobutadiene (7), and 1,4-dihydropyrazine (6). Their dinitro and diamino derivatives were also investigated. Stabilizing or destabilizing energetic effects were quantified by means of the isodesmic reaction procedure at the MP2/6-31G*//HF/3-21G level, and calculated molecular electrostatic potentials (HF/STO-5G//HF/3-21G) were used as a probe of electron delocalization. Our results do not show extensive delocalization in the π systems of any one of the three parent molecules. The destabilization found for 1 and 7 is attributed primarily to strain and to repulsion between the localized π electrons in the C=C and C=N bonds, respectively. However, 6 is significantly stabilized, presumably due to limited delocalization of the nitrogen lone pairs. NH2 groups are highly stabilizing, apparently because of lone pair delocalization. NO2 is neither uniformly stabilizing nor destabilizing.

Application of Eddy Currents in Processed Materials Structural Evaluation

2012 ◽  
Vol 730-732 ◽  
pp. 715-720
Author(s):  
Telmo G. Santos ◽  
João Faria ◽  
Pedro Vilaça ◽  
R.M. Miranda
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Eddy Currents ◽  
Microstructural Analysis ◽  
Structural Features ◽  
Crystal Defects ◽  
Electrical Currents ◽  
Friction Stir ◽  
Characterization Technique ◽  
Physical Phenomena

Eddy currents are based on electromagnetic induction and analysis of electrical currents on conductive materials. This method is used for thickness measurements, corrosion and defects detection, electrical conductivity and magnetic permeability measurements. Recently, it has been exploited as a materials characterization technique, namely in solid state welding, since, compared to hardness, it is based in distinct physical phenomena. Electrical conductivity is controlled by electronic mobility, while hardness depends on crystal defects and thus a scale factor exists. This paper presents results of this characterization technique applied to multipass solid state friction stir processing (FSP) of AA1100 alloy. These results were compared to microstructural analysis and hardness measurements and show that eddy current is a feasibly, reliable and expedite technique to characterize processed materials. The electrical conductivity measured by eddy currents, maps more precisely structural features, while hardness does not. Measurement of electrical conductivity field suggests having potential to constitute an alternative and/or complement to hardness evaluation with the further advantage of being a non-destructive method.

Structural diversity of new solid-state luminophores based on quinoxaline-β-ketoiminate boron difluoride complexes with remarkable fluorescence switching properties

2015 ◽  
Vol 51 (13) ◽  
pp. 2656-2659 ◽  
Author(s):  
Chia-Wei Liao ◽  
Rajeswara Rao M. ◽  
Shih-Sheng Sun
Keyword(s):  
Solid State ◽  
Structural Diversity ◽  
Acid Base ◽  
Fluorescence Switching ◽  
Solid State Fluorescence ◽  
Boron Difluoride

Highly tunable organoboron luminophores with intense solid-state fluorescence showed outstanding photoswitching properties modulated by acid/base vapors.

Benzothiazole–pyrimidine-based BODIPY analogues: promising luminophores with fluorescence sensing and imaging ability and asymmetrization-induced solid-state emission

2016 ◽  
Vol 45 (43) ◽  
pp. 17274-17280 ◽  
Author(s):  
Xiaoqing Wang ◽  
Qingsong Liu ◽  
Fen Qi ◽  
Lin Li ◽  
Hai-Dong Yu ◽  
...  
Keyword(s):  
Solid State ◽  
Fluorescence Sensing ◽  
Intense Emission ◽  
Boron Difluoride

A series of boron difluoride dyes were demonstrated to possess intense emission both in solution and solid-state. Their fluorogenic sensing and imaging abilities were also investigated.

scholarly journals Layer-by-Layer Structural Identification of 2D Ruddlesden-Popper Hybrid Lead Iodide Perovskites by Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Jeongjae Lee ◽  
Woocheol Lee ◽  
Keehoon Kang ◽  
Takhee Lee ◽  
Sung Keun Lee
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Structural Features ◽  
Layer By Layer ◽  
Lead Iodide ◽  
Materials Properties ◽  
Non Invasive ◽  
Local Bonding ◽  
Halide Perovskites

Application of two-dimensional (2D) organic-inorganic hybrid halide perovskites for optoelectronic devices requires detailed understanding of the local structural features including the Pb-I bonding in the 2D layers and the capping ligand-perovskite interaction. In this study, we show that <sup>1</sup>H and <sup>207</sup>Pb solid-state Nuclear Magnetic Resonance (NMR) spectroscopy can serve as a non-invasive and complementary technique to quantify the composition and to probe the local structural features of 2D Ruddlesden-Popper phase BA<sub>2</sub>MA<i><sub>n</sub></i><sub>-1</sub>Pb<i><sub>n</sub></i>I<sub>3<i>n</i>+1</sub> (<i>n</i>=1-4) with butylammonium (BA) spacers. <sup>207</sup>Pb echo and <sup>1</sup>H-detected <sup>207</sup>Pb→<sup>1</sup>H heteronuclear correlation (HETCOR) experiments enables layer-by-layer structural detection of 2D halide perovskites. We show that the observed correlation between <sup>207</sup>Pb NMR shifts and mean Pb-I bond lengths around each Pb site allows us to probe the local bonding environment of Pb via its <sup>207</sup>Pb NMR shift. We envisage that this technique will be vital for better understanding the materials properties as determined by the local atomistic environments in multi-dimensional halide perovskites.

Phenanthro[9,10-d]imidazole-quinoline Boron Difluoride Dyes with Solid-State Red Fluorescence

2013 ◽  
Vol 15 (7) ◽  
pp. 1768-1771 ◽  
Author(s):  
Weiling Li ◽  
Weiying Lin ◽  
Jiaoliang Wang ◽  
Xiaoyu Guan
Keyword(s):  
Solid State ◽  
Red Fluorescence ◽  
Boron Difluoride
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