Jun-Min Liu

Inherently Chiral Calixarenes: Synthesis, Optical Resolution, Chiral Recognition and Asymmetric Catalysis

Inherently chiral calixarenes, whose chirality is based on the absence of a planar symmetry or an inversion center in the molecules as a whole through the asymmetric array of several achiral groups upon the three-dimensional calix-skeletons, are challenging and attractive chiral molecules, because of their potential in supramolecular chemistry. The synthesis and optical resolution of all varieties of inherently chiral calixarenes are systematically discussed and classified, and their applications in chiral recognition and asymmetric catalysis are thoroughly illustrated in this review.

Highly efficient and stable organic sensitizers with duplex starburst triphenylamine and carbazole donors for liquid and quasi-solid-state dye-sensitized solar cells

Two new D–D–π–π–A type stable organic sensitizers, DT3 and DW3, were successfully synthesized for dye-sensitized solar cells (DSSCs). DT3 displayed η values of 10.03% and 8.05% in liquid and quasi-solid-state DSSCs, respectively, under standard global 1.5 solar conditions, offering an example achieving the highest efficiency to date in quasi-solid-state DSSCs based on pure organic dyes.

Assembly of Robust and Porous Hydrogen-Bonded Coordination Frameworks: Isomorphism, Polymorphism, and Selective Adsorption

By using the tripodal ligand ntb (tris(benzimidazole-2-ylmethyl)amine) and lanthanide nitrate, three isomorphous series of coordination frameworks of the general formula [Ln(ntb)(NO(3))(3)]·solvents (series 1: monoclinic C2/c, Ln = Gd(3+) and Yb(3+); series 2: hexagonal P3(1)/c, Ln = Nd(3+), Eu(3+), Gd(3+), and Er(3+); series 3, cubic Pa3̅, Ln = Gd(3+) and Er(3+); solvent = H(2)O or CH(3)OH) have been assembled and characterized with IR, elemental analyses, and single crystal and powder X-ray diffraction methods. In all isomorphous complexes, analogous [Ln(ntb)(NO(3))(3)] coordination monomers of the same structure act as the building blocks to be assembled via hydrogen bonds into three-dimensional (3D) frameworks. So the complexes of the same lanthanide ion (for example, the Gd(3+) ion) from three isomorphous series form polymorphs, for example, monoclinic polymorph 1-Gd, hexagonal polymorph 2-Gd, and cubic polymorph 3-Gd. The single-crystal analyses revealed that the polymorphism was related to different fashions of hydrogen bonding interactions, which was caused by different crystallization conditions, leading to the formation of different 3D hydrogen-bonded frameworks showing distinct porous and topological structures. The monoclinic and hexagonal crystals contain 1D channels, while the cubic crystal is nonporous. The thermogravimetric analyses indicated that all polymorphic crystals have high thermal stability against the removal of guest molecules, and the robust porosity of the hexagonal crystals has been verified by temperature-dependent single-crystal-to-single-crystal measurements upon guest removal/uptake. The solvents adsorption study disclosed that the porous frameworks show high selectivity of benzene against toluene and xylene, while the gas adsorption measurements indicated a moderate H(2), CO(2), and MeOH storage capacity in contrast to low N(2) uptake. The solid-state photoluminescence of the Eu(3+) and Nd(3+) complexes in the near-infrared and visible region has also been investigated, offering examples with optical properties tunable by means of isomorphous replacement.

Hydrothermal Fabrication of Quasi‐One‐Dimensional Single‐Crystalline Anatase TiO2 Nanostructures on FTO Glass and Their Applications in Dye‐Sensitized Solar Cells

One-dimensional and quasi-one-dimensional semiconductor nanostructures are desirable for dye-sensitized solar cells (DSSCs), since they can provide direct pathways for the rapid collection of photogenerated electrons, which could improve the photovoltaic performance of the device. Quasi-1D single-crystalline anatase TiO(2) nanostructures have been successfully prepared on transparent, conductive fluorine-doped tin oxide (FTO) glass with a growth direction of [101] through a facile hydrothermal approach. The influences of the initial titanium n-butoxide (TBT) concentration, hydrothermal reaction temperature, and time on the length of quasi-1D anatase TiO(2) nanostructures and on the photovoltaic performance of DSSCs have been investigated in detail. A power conversion efficiency of 5.81% has been obtained based on the prepared TiO(2) nanostructure photoelectrode 6.7 μm thick and commercial N719 dye, with a short-circuit current density of 13.3 mA cm(-2) , an open-circuit voltage of 810 mV, and a fill factor of 0.54.

Assembly of a 1D Coordination Polymer through in Situ Formation of a New Ligand by Double C−C Coupling on CHCl3 under Solvothermal Conditions

A rare in situ metal/ligand reaction has been observed during the assembly of a manganese-coordination polymer under solvothermal conditions, which leads to double C-C coupling on CHCl(3) involving cleavage of three C-Cl bonds and the formation of two new C-C bonds at the same carbon center.

Anion effect on the structural diversity of three 1D coordination polymers based on a pyridyl diimide ligand

Three new zinc coordination polymers, namely {[Zn(4-pmntd)Cl2]·H2O}n (1), {[Zn(4-pmntd)(CH3CN)4]·(ClO4)2·H2O}n (2), and {[Zn(4-pmntd)(H2O)4]·(CF3SO3)2·3H2O}n (3) (4-pmntd = N,N′-bis(4-pyridylmethyl)-naphthalene diimide) have been synthesized by reactions of 4-pmntd with ZnCl2, Zn(ClO4)2, and Zn(CF3SO3)2, respectively. Compound 1 is an unusual one-dimensional (1D) single-stranded double helical chain containing tubular channels; 2 is an uncommon 1D zigzag chain arranged in a cross-like fashion to generate a 3D plywood-like array; 3 is a typical 1D zigzag chain arranged in a parallel array containing 1D quadrangle channels to accommodate the counter anions and water molecules. The structural diversity in these compounds is attributed to different coordination abilities, sizes, and geometries of counter anions. The anion exchange property of 3 was investigated.

Starburst triarylamine based dyes bearing a 3,4-ethylenedioxythiophene linker for efficient dye-sensitized solar cells.

Starburst triarylamine-based organic dyes (D1, D2, and D3) have been synthesized. For the three designed dyes, the starburst triarylamine group, thiophene (or 3,4-ethylenedioxythiophene), and cyanoacetic acid take the role of electron donor, π-conjugation bridge, and electron acceptor, respectively. These compounds are characterized by photophysical, electrochemical, and theoretical computational methods. Nanocrystalline TiO2-based dye-sensitized solar cells were fabricated using these molecules as light-harvesting sensitizers. The overall efficiencies of the sensitized cells range from 5.48 to 6.15%. It was found that the introduction of the EDOT group in D3 bathochromically extended the absorption spectra, resulting in a leap in the photovoltaic performance in comparison to D2. Incorporation of a hydrophobic carbazole-containing segment at D2 relative with D1 retarded the electron transfer from TiO2 to the oxidized dye or electrolyte, leading to an increase of electron lifetime.

A multifunctional poly-N-vinylcarbazole interlayer in perovskite solar cells for high stability and efficiency: a test with new triazatruxene-based hole transporting materials

The hydrophobic and conductive polymer poly-N-vinylcarbazole (PVK) has been successfully utilized as a multifunctional interlayer between perovskite and the hole transporting material (HTM) for highly stable and efficient perovskite solar cells (PSCs) for the first time. The very thin PVK interlayer can not only protect the perovskite structure from moisture and degradation, but also modulate the interface to reduce charge recombination and promote hole transportation simultaneously. Benefited by coupling this PVK-protection method with the molecular design of an economical and synthetically facile triazatruxene-based HTM (SP-12) featuring good stability, planarity and hole mobility, a reliable power conversion efficiency of 18.8% has been achieved, which is superior to that using the well-studied spiro-OMeTAD (16.9%), demonstrating a promising fabrication approach to efficient and long-term stable PSCs.

Chelant extraction of heavy metals from contaminated soils using new selective EDTA derivatives

Soil washing is one of the few permanent treatment alternatives for removing metal contaminants. Ethylenediaminetetraacetic acid (EDTA) and its salts can substantially increase heavy metal removal from contaminated soils and have been extensively studied for soil washing. However, EDTA has a poor utilization ratio due to its low selectivity resulting from the competition between soil major cations and trace metal ions for chelation. The present study evaluated the potential for soil washing using EDTA and three of its derivatives: CDTA (trans-1,2-cyclohexanediaminetetraacetic acid), BDTA (benzyldiaminetetraacetic acid), and PDTA (phenyldiaminetetraacetic acid), which contain a cylcohexane ring, a benzyl group, and a phenyl group, respectively. Titration results showed that PDTA had the highest stability constants for Cu(2+) and Ni(2+) and the highest overall selectivity for trace metals over major cations. Equilibrium batch experiments were conducted to evaluate the efficacy of the EDTA derivatives at extracting Cu(2+), Zn(2+), Ni(2+), Pb(2+), Ca(2+), and Fe(3+) from a contaminated soil. At pH 7.0, PDTA extracted 1.5 times more Cu(2+) than did EDTA, but only 75% as much Ca(2+). Although CDTA was a strong chelator of heavy metal ions, its overall selectivity was lower and comparable to that of EDTA. BDTA was the least effective extractant because its stability constants with heavy metals were low. PDTA is potentially a practical washing agent for soils contaminated with trace metals.

Stable organic dyes based on the benzo[1,2-b:4,5-b′]dithiophene donor for efficient dye-sensitized solar cells

Two novel arylamine-free organic compounds (CYF1 and CYF2) incorporating a substituted benzo[1,2-b:4,5-b′]dithiophene unit as the electron donor were synthesized and used as sensitizers for dye-sensitized solar cells (DSSCs). The relationship between the chemical structure and photovoltaic performance was investigated. A higher molar absorption coefficient, longer electron lifetime, and larger adsorption amount were observed for sensitizer CYF1, which contains a single π bridge and anchoring unit, compared with CYF2 with twin π bridges and anchoring units. As a result, under standard global AM 1.5 solar conditions, the device based on CYF1 sensitizer gave a higher conversion efficiency of 8.02% than that based on CYF2. This is the highest value for amine-free organic sensitizers with no strong donor units. Moreover, the CYF1- and CYF2-sensitized DSSCs exhibited excellent stability under 1000 W m2 light soaking at 60 °C for 600 h. This is the first example of organic sensitizers based on benzo[1,2-b:4,5-b′]dithiophene donors for efficient dye-sensitized solar cells.