Xiao-Ming Jiang

Inorganic Supramolecular Compounds with 3-D Chiral Frameworks Show Potential as Both Mid-IR Second-Order Nonlinear Optical and Piezoelectric Materials

Two inorganic supramolecular compounds, (Hg(6)P(3))(In(2)Cl(9)) (1) and (Hg(8)As(4))(Bi(3)Cl(13)) (2), which have chiral 3-D host frameworks with guest moieties filling the helical tunnels, have been synthesized. They both have large second-harmonic generation efficiencies, and compound 2 also exhibits obvious single-crystal piezoelectric performance. Theoretical studies from first-principles calculations were performed on their nonlinear optical (NLO) and piezoelectric properties, and results indicate that good NLO and piezoelectric materials can be obtained by designing both complicated polycations and polyanions with large molecular polarizability as functional components rather than traditional single polyanions.

Two phases of Ga2S3: promising infrared second-order nonlinear optical materials with very high laser induced damage thresholds

Two phases of Ga2S3 with different space groups Cc and F3m were synthesized in pure phase by a facile boron–sulfur–metallic oxide reaction. They both have a good transparency in the wavelength range of 0.44–25 μm and exhibit comparatively large second-harmonic generation (SHG) effects of about 0.7 and 0.5 times that of commercial KTiOPO4 (KTP), for the monoclinic and cubic Ga2S3 respectively. The monoclinic Ga2S3 is phase-matchable at the wavelength of 1910 nm while the cubic phase is non-phase-matchable. In order to study their powder laser induced damage threshold (LIDT) properties, a single pulse powder LIDT measurement method was proposed and it was found that they have very high powder LIDTs of about 30 and 100 times that of AgGaS2 (AGS), respectively for the monoclinic and cubic phase, under a single pulse 1064 nm laser radiation with a pulse width τp of 8 ns. To gain further insights into the nonlinear optical (NLO) and LIDT properties of the monoclinic and cubic Ga2S3, calculations of second-order NLO susceptibility and lattice energy density (LED) were also performed to explain their SHG efficiencies and high LIDTs.

Stabilization of (SnS4)4− anion by coordinating to [TM(π-conjugated-ligand)m]n+ complex: a chain-like thiostannate(IV) {[Mn(phen)]2(SnS4)}n·nH2O exhibiting an unprecedented link mode of the (SnS4)4− anion

The stabilization of the (SnS4)4− anion in the coordination of [Mn(phen)]2+ complexes brings about a novel compound {[Mn(phen)]2(SnS4)}n·nH2O (1), in which an unprecedented link mode of the (SnS4)4− anion is observed. Theoretical calculations indicate that TM complexes with big π-conjugated ligands, such as [Mn(phen)]2+, can serve as an excellent electron reservoir to stabilize the (SnS4)4− anion in 1, despite its strong condensation tendency. Magnetic measurements show the presence of strong antiferromagnetic interactions between the Mn2+ ions in 1.

A highly stable 3D acentric zinc metal-organic framework based on two symmetrical flexible ligands: high second-harmonic-generation efficiency and tunable photoluminescence.

A 3D metal-organic framework (MOF), [Zn(BPHY)(SA)]n (1; BPHY = 1,2-bis(4-pyridyl)hydrazine, H2SA = succinic acid), which crystallizes in a noncentrosysmmetric space group (Cc), has been solvothermally obtained and testified to be a good nonlinear-optical material with the largest second-harmonic-generation response among the known MOFs based on sysmmetric ligands and high stability. Ultraviolet-to-visible tunable emission for 1 is observed.

Crystal structures and optical properties of iodoplumbates hybrids templated by in situ synthesized 1,4-diazabicyclo[2.2.2]octane derivatives

We investigate the impact of different derivatives of 1,4-diazabicyclo[2.2.2]octane on the crystal structures of iodoplumbates by systematically increasing the size of the same organic amine, and present two new 1-D iodoplumbates. Optical studies reveal the semiconductor characteristics of all as-synthesized iodoplumbate hybrids.

Large Crystal Growth and New Crystal Exploration of Mid-Infrared Second-Order Nonlinear Optical Materials

Mid-IR second-order NLO crystal is indispensable in the frequency conversion applications in the mid-IR region. Compared with DUV and UV/Vis/near-IR NLO crystals, practical mid-IR NLO crystals are relatively rare, and many of them are still at the stage of laboratory research. This chapter reviews the recent progress on the mid-IR NLO crystals, which mainly includes growing the classical mid-IR NLO crystals into large high-quality ones or into quasi-phase-matching structures that are suitable for the laser devices by various growth methods and exploring new potential mid-IR NLO crystals by introducing new design and synthesis strategies. Recent mid-IR NLO crystals can be divided into four categories, i.e., classical binary and ternary metal pnictides and chalcogenides, quaternary metal chalcogenides, binary and ternary metal halides, and different-bond-type hybrid compounds that contain at least two types of obviously different chemical bonds in the crystal structures. Metal pnictides and chalcogenides have got much attention on growing large crystals. Different-bond-type hybrid is a new family of mid-IR NLO materials, and many of them were found in the last decade. In metal halide system, both progress in growing large crystals and discovering new ones have been made.

Reversible Single-Crystal-to-Single-Crystal Transformation and Magnetic Change of Nonporous Copper(II) Complexes by the Chemisorption/Desorption of HCl and H2O

Vapor-responsive magnetic materials are highly promising for applications as chemical switches or sensors. Compared with porous materials, nonporous species benefit in overcoming the intrinsic conflict between magnetic exchange and porosity but usually suffer from the powdering of single crystals, which hinders the understanding of the structural nature of vapor response and magnetic switch. Single-crystal-to-single-crystal (SCSC) transformation of nonporous compounds through the desorption/absorption of gaseous HCl is unprecedented. Reported here is a discrete nonporous copper(II) complex, (H3O)[K(15-crown-5)2][CuCl4], that exhibits reversible SCSC transformation and magnetic change by the chemisorption/desorption of HCl and H2O. Significant changes in the coordination number (4 ↔ 3), space group (P1̅ ↔ P21/c), color (green ↔ red), and magnetic behavior (antiferromagnetic ↔ paramagnetic) were found during the SCSC transformation.

Design Strategy for Improving Optical and Electrical Properties and Stability of Lead-Halide Semiconductors

Broad absorption, long-lived photogenerated carriers, high conductance, and high stability are all required for a light absorber toward its real application on solar cells. Inorganic-organic hybrid lead-halide materials have shown tremendous potential for applications in solar cells. This work offers a new design strategy to improve the absorption range, conductance, photoconductance, and stability of these materials. We synthesized a new photochromic lead-chloride semiconductor by incorporating a photoactive viologen zwitterion into a lead-chloride system in the coordinating mode. This semiconductor has a novel inorganic-organic hybrid structure, where 1-D semiconducting inorganic lead-chloride nanoribbons covalently bond to 1-D semiconducting organic π-aggregates. It shows high stability against light, heat, and moisture. After photoinduced electron transfer (PIET), it yields a long-lived charge-separated state with a broad absorption band covering the 200-900 nm region while increasing its conductance and photoconductance. This work is the first to modify the photoconductance of semiconductors by PIET. The observed increasing times of conductivity reached 3 orders of magnitude, which represents a record for photoswitchable semiconductors. The increasing photocurrent comes mainly from the semiconducting organic π-aggregates, which indicates a chance to improve the photocurrent by modifying the organic component. These findings contribute to the exploration of light absorbers for solar cells.

Large mid-IR second-order nonlinear-optical effects designed by the supramolecular assembly of different bond types without IR absorption.

Two new different-bond-type hybrid compounds, (Hg6P4Cl3)(PbCl3) (1) and (Hg23P12)(ZnCl4)6 (2), with supramolecular interactions between host and guest moieties, which based on metal-pnicogen, pnicogen-pnicogen, and metal-halogen bonds were obtained by solid-state reactions. Compounds 1 and 2 show large second-harmonic-generation (SHG) activity and are transparent in the wide mid-IR region, providing an effective route for searching new IR nonlinear-optical material systems by combining two or more different bond types with no IR absorption within a single compound through supramolecular assembly. Theory predications based on first-principles calculations are also performed on the SHG properties of 1 and 2.

A 3D metal–organic framework built from vanadate clusters and diamond chains showing weak ferromagnetic single-chain-magnet like behavior

Magnetically weakly coupled diamond chains in the 3D metal–organic framework are well separated by diamagnetic [V4O12]4− cluster units and semi-rigid ligands, and exhibit not only weak ferromagnetic interactions with frustrated spin canting but also single-chain magnets with slow magnetic relaxation below 3.4 K.