Coordination Ability Of Ligand Research Articles

24.8%-efficient planar perovskite solar cells via ligand-engineered TiO2 deposition

<h2>Summary</h2> Planar perovskite solar cells (PSCs) have been extensively researched as a promising photovoltaic technology, wherein the electron extraction and transfer play a crucial role in the power conversion efficiency (PCE). Here, we proposed a ligand-engineered deposition strategy based on the coordination ability of ligands (e.g., tartaric acid) to regulate TiO₂ film and interfacial structure. This strategy can effectively inhibit particle aggregation of TiO₂ film through the steric hindrance of assembled ligands. Furthermore, the decreased interfacial contact impedance and enhanced electron extraction are achieved between TiO₂ and perovskite, due to the smooth topography and cross-linked structure formed by tartaric acid that bonds with Ti and Pb atoms. Accordingly, an impressive PCE of 24.8% with a fill factor exceeding 0.83 is successfully obtained, which is the highest PCE among TiO₂-based planar PSCs reported so far. In addition, unencapsulated PSCs can maintain ∼95% of initial efficiency upon exposure to ambient air for 2,000 h.

Selective separation between UO22+ and Pu4+ by novel tetradentate chelate phenanthroline diamide ligand in 1-octanol

In the traditional spent nuclear fuel reprocessing process, tri-n-butyl phosphate (TBP) combined with reducing agents is employed for co-extraction of UO22+and Pu4+ and their separation from each other, which makes the system very complicated and also brings phosphorus pollution problems. Herein, a series of environmentally friendly tetradentate phenanthroline-diamide ligands in line with the “CHON” principle were synthesized and applied to the selective separation between UO22+ and Pu4+ in 1-octanol system. The sifted ligand, N,N′-diethyl-N,N′-diphenyl-2,9-diamide-1,10-phenanthroline (Et-Ph-DAPhen), can co-extract UO22+ and Pu4+ under high acidity, but hardly extract Pu4+ under low acidity, which substantiates the applicability of this extraction system for selective separation of UO22+ from Pu4+. The novel scheme achieving the separation without any reductant but only by adjusting the acidity of the aqueous phase will simplify the separation process and improve the existing scheme. The coordination chemistry research of the ligand with UO22+ and Pu4+ confirms that the ligand generates both M: L = 1:1 and 1:2 complexes with Pu4+ but only M: L = 1:1 complex with UO22+. The coordination ability of ligand with shorter carbon chains is slightly stronger than that with longer chains. The ligands and diluents in line with the “CHON” principle will be helpful to reduce environmental pollution and pressure of subsequent waste treatment. No reducing agent process contributes to simplify the operation steps and reduce the complexity of the process. The coordination chemistry offers further comprehension of the separation mechanism and guides the synthesis of efficient separation ligands.

Component selection in the self-assembly of palladium(II) nanocages and cage-to-cage transformations.

Dynamic supramolecular systems involving a tetratopic palladium(II) acceptor and three different pyridine- and imidazole-based donors have been used for self-selection by a synergistic effect of morphological information and coordination ability of ligands through specific coordination interactions. Three different cages were first synthesized by two-component self-assembly of individual donor and acceptor. When all four components were allowed to interact in a reaction mixture, only one out of three cages was isolated. The preferential binding affinity towards a particular partner was also established by transforming a non-preferred cage into a preferred cage by interaction with the appropriate ligand. Computational studies further supported the fact that coordination interaction of imidazole moiety to Pd(II) is enthalpically more preferred compared to pyridine, which drives the selection process. Analysis of crystal packing of both complexes indicated the presence of strong hydrogen bonds between nitrate and water molecules and also H-bonded 3D networks of water. Both complexes exhibit promising proton conductivity (10(-5) to ca. 10(-3) S cm(-1) ) at ambient temperature under a relative humidity of circa 98 % with low activation energy.

Modular Spiro Bidentate Nitrogen Ligands – Synthesis, Resolution and Application in Asymmetric Catalysis

AbstractA family of new modular, chiral, bidentate, nitrogen‐donor ligands containing the large spirobi(chroman) backbone 1 (SPAN) has been prepared. Enantiopure diamines containing the nitrogen donors at the 8,8′ positions of spirobi(chroman) 1 have been synthesized through the resolution of the 8,8′‐diamino racemate 3. Accordingly, secondary and tertiary amines [(+)‐6/(–)‐6 and (+)‐5/(–)‐5, respectively] and imino derivatives [(+)‐7/(–)‐7] were obtained in both enantiomeric forms. A new SPAN derivative incorporating aldehyde groups at the 8,8′ positions of the spirobi(chroman) unit [(+)‐9/(–)‐9] has been synthesized with the aim to extend the ligand library by means of Schiff base chemistry. The derivatization of the isolated enantiomers of 9 obtained by diastereomer resolution gave derivatives containing the nitrogen atoms at the benzylic positions. The syntheses of ligands (+)‐10/(–)‐10, (+)‐11 and (+)‐12 illustrate the scope of this methodology. The coordination ability of ligand (–)‐3 has been tested by the synthesis and characterization of complex [Pd(OAc)2{(–)‐3}] [(–)‐13]. Some preliminary results related to the oxidative kinetic resolution of 1‐phenylethanol with this Pd complex are reported.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2008)

Growth of Well‐Aligned γ‐MnO2 Monocrystalline Nanowires Through a Coordination‐Polymer‐Precursor Route.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Growth of well-aligned gamma-MnO2 monocrystalline nanowires through a coordination-polymer-precursor route.

A new coordination-polymer-precursor route has been developed to synthesize nanowires under hydrothermal conditions. In the present work, well-aligned gamma-MnO(2) nanowires, growing along the [0 0 2] axis, have successfully been prepared by selecting an appropriate coordination polymer [[Mn(SO(4))(4,4'-bpy)(H(2)O)(2)](n)] as precursor. In comparison with the experimental results from other coordination-polymer precursors, it is found that only [[Mn(SO(4))(4,4'-bpy)(H(2)O)(2)](n)] is appropriate for the formation of gamma-MnO(2) crystal lattices during the process of oxidization. The IR absorption spectra of as-obtained precipitates at different reaction intervals minutely describe the reaction process, due to the different coordination abilities of ligands in the coordination polymer. More evidence about the mechanism will be further explored in the future study. Further observations show the ordered alignment of nanowires' tops and such well-aligned nanowires provide more possible applications in lithium batteries.