Assigning the Absolute Configurations of Chiral Primary Amines Based on Experimental and DFT-Calculated 19F Nuclear Magnetic Resonance

In this work, a novel method for assigning the absolute configuration of a chiral primary amine has been developed based on the experimental and DFT-calculated 19F NMR chemical shift differences of its derived two fluorinated amides by reacting with two enantiomers of a chiral derivatizing agent FPP (α-fluorinated phenylacetic phenylselenoester) separately. Comparing the experimental chemical shift difference Δδα-FR,S of (R)-FPA-amide/(S)-FPA-amide with the calculated Δδα-FR,S of (R)-FPA-(R)-amide/(S)-FPA-(R)-amide, if the experimental Δδα-FR,S has the same symbol (positive or negative) as one of the theoretical Δδα-FR,S, the assigned configuration of the amine is considered to be consistent with the theoretical one. Our method could be applied to a broad substrate scope avoiding wrong conclusion due to empirical judgment

Mechanistic study of visible light-driven CdS or g-C₃N₄-catalyzed C–H direct trifluoromethylation of (hetero)arenes using CF₃SO₂Na as the trifluoromethyl source

The mild and sustainable methods for C–H direct trifluoromethylation of (hetero)arenes without any base or strong oxidants are in extremely high demand. Here, we report that the photo-generated electron-hole pairs of classical semiconductors (CdS or g-C3N4) under visible light excitation are effective to drive C–H trifluoromethylation of (hetero)arenes with stable and inexpensive CF3SO2Na as the trifluoromethyl (TFM) source via radical pathway. Either CdS or g-C3N4 propagated reaction can efficiently transform CF3SO2Na to [rad]CF3 radical and further afford the desired benzotrifluoride derivatives in moderate to good yields. After visible light initiated photocatalytic process, the key elements (such as F, S and C) derived from the starting TFM source of CF3SO2Na exhibited differential chemical forms as compared to those in other oxidative reactions. The photogenerated electron was trapped by chemisorbed O2 on photocatalysts to form superoxide radical anion (O2[rad]−) which will further attack [rad]CF3 radical with the generation of inorganic product F− and CO2. This resulted in a low utilization efficiency of [rad]CF3 (&lt;50%). When nitro aromatic compounds and CF3SO2Na served as the starting materials in inert atmosphere, the photoexcited electrons can be directed to reduce the nitro group to amino group rather than being trapped by O2. Meanwhile, the photogenerated holes oxidize SO2CF3− into [rad]CF3. Both the photogenerated electrons and holes were engaged in reductive and oxidative paths, respectively. The desired product, trifluoromethylated aniline, was obtained successfully via one-pot free-radical synthesis.</p

Tuning electronic and optical properties of CsPbI3 by applying strain: A first-principles theoretical study

In this study, the effect of hydrostatic strain on the structural, electronic and optical properties of CsPbI3 was investigated by using first-principles calculations. The calculated results show that the band gap of CsPbI3 can be tuned from 1.03 to 2.14 eV when the strain ranges from - 5% to 5%. A suitable band gap (1.34 eV) of CsPbI3 can be obtained under a strain of -3% (1.40 GPa). The calculated elastic constants further imply that this compound is stable under the abovementioned condition. Moreover, bandgap narrowing leads to the stronger optical absorption in the visible light region

Mononuclear, trinuclear, and hetero-trinuclear supramolecular complexes containing a new tri-sulfonate ligand and cobalt(II)/copper(II)-(1, 10-phenanthroline)(2) building blocks

Novel mononuclear, trinuclear, and hetero-trinuclear supermolecular complexes, [Co(phen)(2)(H2O)(HTST)] center dot 2H(2)O (1), [CO3(phen)(6) (H2O)(2)(TST)(2)]center dot 7H(2)O (2), and [CO2Cu(phen)(6)(H2O)(2)(TST)(2)]center dot 10H(2)O (3), have been synthesized by the reactions of a new tri-sulfonate ligand (2,4,6-tris(4-sulfophenylamino)- 1,3,5-triazine, H3TST) with the M2+ (M = Co, Cu) and the second ligand 1, 10-phenanthroline (phen). Complex 1 contains a cis-Co(II)(phen)(2) building block and an HTST as monodentate ligand; complex 2 consists of two TST as bidentate ligands connecting one trans- and two cis-Co(II)(phen)(2) building blocks; complex 3 is formed by replacing the transCo(II)(phen)(2) in 2 with a trans-Cu(II)(phen)(2), which is the first reported hetero-trinuclear supramolecular complex containing both the Co(II)(phen)(2) and Cu(II)(phen)(2) as building blocks. The study shows the flexible multifunctional self-assembly capability of the H3TST ligands presenting in these supramolecular complexes through coordinative, H-bonding and even pi-pi stacking interactions. The photo luminescent optical properties of these complexes are also investigated and discussed as well as the second-order nonlinear optical properties of 1. (C) 2007 Elsevier Inc. All rights reserved

CCDC 648028: Experimental Crystal Structure Determination

Related Article: Yunfang Yu, Yongqin Wei, R.Broer, Rongjian Sa, Kechen Wu|2008|J.Solid State Chem.|181|539|doi:10.1016/j.jssc.2007.12.028,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 648026: Experimental Crystal Structure Determination

Related Article: Yunfang Yu, Yongqin Wei, R.Broer, Rongjian Sa, Kechen Wu|2008|J.Solid State Chem.|181|539|doi:10.1016/j.jssc.2007.12.028,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 648027: Experimental Crystal Structure Determination

Related Article: Yunfang Yu, Yongqin Wei, R.Broer, Rongjian Sa, Kechen Wu|2008|J.Solid State Chem.|181|539|doi:10.1016/j.jssc.2007.12.028,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Exploring Second-Order Nonlinear Optical Properties and Switching Ability of a Series of Dithienylethene-Containing, Cyclometalated Platinum Complexes: A Theoretical Investigation

The second-order nonlinear optical (NLO) properties of a series of dithienylethene- (DTE-) containing Pt­(II) complexes have been investigated by density functional theory calculations. The first hyperpolarizabilities β of studied systems can be greatly enhanced by simple ligand substitutions. Because of the nature of DTE units, the β values also can be varied by the use of lights in the studied systems. The highest β difference between photoisomers can over 1000 × 10^–30 esu, with the contrast around five times. Thus, the studied systems can act as effective photoswitchable second-order NLO materials. The time-dependent density functional theory calculations revealed that the charge transfer patterns of studied systems have special characters compared to other reported DTE-containing NLO switched chromogens, the DTE units mainly act as electron-donors in studied systems, and the variation of β can be viewed as alternation of donor abilities of DTE units; thus, our work also proposed a new mechanism for designing photoswitched NLO multifunctional materials

Breaking the limitation of sodium-ion storage for nanostructured carbon anode by engineering desolvation barrier with neat electrolytes

In the past, most of the studies monotonously focused on developing electrode materials for sodium ion batteries (SIBs), while the compatibility effects and mechanism of electrolytes with material microstructures on the sodiation behavior are barely involved. Here, we demonstrate the sodium-ion storage behavior of carbon anode in neat ether electrolytes with outstanding ion diffusion kinetics at electrode surface that breaks its innate limitation. Porous nanocarbon with small interlayer spacing but very high surface area exhibits a record high ICE over 91.1% and exceptional rate capability for Na-ion storage in ether -based electrolytes. This is due to the remarkably reduced Na thorn desolvation barrier in ether electrolytes (-94.6 meV) that is less than one-third of that in ester electrolytes (-307.8 meV). The strong interaction of Na-ions with ester electrolytes and their decom- position on electrode surface can be suppressed by adopting ether solvents owing to lower Gibbs free energies of solvation and Na thorn desolvation energy as revealed by DFT calculations. For electrode materials working with ether electrolytes, a large surface area is critical for better electrochemical performance. This study provides a reliable regulation parameter for tailoring electrolytes with materials that offers promising potential for nano - structured materials toward high -rate rechargeable devices