Photoinduced large magnetic change at room temperature and radical-quenched spin glass in a cyanide-bridged MnII-FeIII compound.

By the coordination assembly of a redox photoactive functional motif and a cyanide-bridged moiety, a cyanide-bridged MnII-FeIII compound with large photoinduced magnetic change at room-temperature due to photoinduced electron transfer was obtanied. This compound also shows unprecedented radical-quenched spin glass in molecule based magnets.

Photochromic Semiconductive Hydrogen-Bonded Organic Framework (HOF) with Broadband Absorption.

Semiconductors with broadband photoelectric response have important practical needs in many aspects such as solar energy conversion, photocatalysis, and photodetection. We synthesized the first photochromic semiconductive hydrogen-bonded organic framework (HOF), [H2(bpyb)](H2PO4)2·2H2O (1), using the polycyclic viologen cation [H2(bpyb)] (bpyb = 1,4-bis(tetrapyridyl)benzene). After 1 s of xenon lamp irradiation, compound 1 showed a visible color change from the initial yellowish to dark purple after continuous irradiation. The photoinduced radical product has an absorption band covering 200-1700 nm, which is wider than the absorption ranges of silicon and perovskites. It produced photocurrent when irradiated with a xenon lamp or a laser (355, 532, or 808 nm). The on/off ratio of the current (Iirr/Idark) can be as high as 300 times under the irradiation of the 808 nm laser with a power of 1.9 W cm-2. In addition, under the 808 nm light source, the on/off ratio of 1B is 35 times that of 1A.

Photochromic Coordination Compound: Oxygen-Assisted Photoinduced Color Change for Triplet Oxygen Detection.

Detection of oxygen though color change is highly desirable for rapid qualitative analysis like the case of pH test papers. This work demonstrates 3O2-assisted photoinduced color change of a new photochromic coordination compound [Zn(4-aminopyridine)2Cl2] (ZnaPyCl), which represents the first photochromic compound with a selective 3O2 detection ability. The compound underwent photoinduced intraligand charge separation and formed a stable diradical-like triplet species in the solid state or in frozen solution, accompanied by conversion of triplet oxygen to singlet oxygen.

Photoinduced Electron-Transfer (PIET) Strategy for Selective Adsorption of CO2 over C2 H2 in a MOF.

Similarities in sizes, shapes, and physical properties between carbon dioxide (CO2 ) and acetylene (C2 H2 ) make it a great challenge to separate the major impurity CO2 from products in C2 H2 production. The use of porous materials is an appealing path to replace current very costly and energy-consuming technologies, such as solvent extraction and cryogenic distillation; however, high CO2 /C2 H2 uptake ratio with minor adsorption of C2 H2 at standard pressure was only unexpectedly observed in scarce examples in recent years although the related research started early at 1950s, and general design strategies to realize this aim are still absent. This work has successfully developed an efficient PIET strategy and obtained the second highest CO2 /C2 H2 adsorption ratio for porous materials in a proof-of-concept MOF with a photochromism-active bipyridinium zwitterion. An unprecedented photocontrollable gate effect, owing to change of interannular dihedral after photoinduced generation of radical species, was also observed for the first time. These findings will inspire design and synthesis of porous materials for high efficient gas adsorption and separation.

Photochromic Lanthanide(III) Materials with Ion Sensing Based on Pyridinium Tetrazolate Zwitterion.

Lanthanide(III) ion (Ln(III)) sensing has become a major research area owing to its intriguing prospect in clinic, biology, and environmental studies. However, the existing methods have limitations like requirement of expensive instrumentation, long analytical times, and sample pretreatments, revealing the necessity of other methods. In this work, by using N-methyl-4-pyridinium tetrazolate (mptz) zwitterion as an electron acceptor, we obtained several new Ln(III) compounds with electron-transfer (ET) photochromic properties: [Ln(NO3)3(H2O)4]·mptz [Ln = Sm (1), Eu (2), Gd (3), La (4), Ce (5), Pr (6), Nd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14)]. Notably, different Ln(III) ions in these compounds can be visually identified by their different photoinduced color changes related to the ET process. This work may not only contribute to the more understanding of the structure-photosensitivity relationships of pyridinium-based compounds, but also provide a new approach for Ln(III) ion sensing.

Energy-dependent photochromism at room temperature for visually detecting and distinguishing X-rays.

A radiochromic material with energy-dependent X-ray-induced photochromism was obtained by incorporating a radiosensitive glycolate ligand into an electron-transfer photochromic metalloviologen system. It is highly promising for detecting soft X-rays with energies less than 2 keV and may find application in qualitatively and visually distinguishing the energy range of X-rays.

An inorganic-organic hybrid photochromic material with fast response to hard and soft X-rays at room temperature.

A photochromic compound with fast response to Mo-Kα (4 min) and Al-Kα (1 s) X-rays was synthesized using a cluster of high-Z atoms and a flexible viologen zwitterion. The coloration time of 1 s when exposed to soft X-rays is the recorded minimum for X-ray-induced photochromic materials, indicating a potential to detect low-energy X-rays.

Single-component small-molecule white light organic phosphors.

White light emission from single-component small organic triazole molecules in the solid state was observed for the first time. This unusual intrinsic broadband emission, stemming from the supramolecular aggregate instead of the excimer, can be tuned by controlling the degree of electron delocalization and intensities of intermolecular interactions.

N-Methyl-4-pyridinium Tetrazolate Zwitterion-Based Photochromic Materials.

N,N'-Disubstituted bipyridinium (viologen) and N-monosubstituted bipyridinium compounds are well known for their electron-transfer (ET) photochromic behavior. Their modification has exclusively focused on the N-substituents to date. For the first time, we have studied the photochromic behavior when one pyridyl ring of the bipyridinium is substituted with a multifunctional azole group, and have found that two new coordination compounds based on N-methyl-4-pyridinium tetrazolate (mptz) zwitterion, [Zn(mptz)2 Br2 ] (1) and [Cd3 (mptz)2 Cl6 ]n ⋅4n H2 O (2), exhibit typical ET photochromic behavior owing to photoinduced ET from halogen anion to the mptz ligand. This work demonstrates a new simple, neutral photoactive molecule with electron-accepting ability, which may act as a photoactive component for materials with potential photoswitching and photocatalysis applications.

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.

Photochromism and Photomagnetism of a 3d-4f Hexacyanoferrate at Room Temperature.

Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)6·2H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds.

Semiconductive 3-D haloplumbate framework hybrids with high color rendering index white-light emission.

Single-component white light materials may create great opportunities for novel conventional lighting applications and display systems; however, their reported color rendering index (CRI) values, one of the key parameters for lighting, are less than 90, which does not satisfy the demand of color-critical upmarket applications, such as photography, cinematography, and art galleries. In this work, two semiconductive chloroplumbate (chloride anion of lead(ii)) hybrids, obtained using a new inorganic-organic hybrid strategy, show unprecedented 3-D inorganic framework structures and white-light-emitting properties with high CRI values around 90, one of which shows the highest value to date.

Electron-transfer photochromism to switch bulk second-order nonlinear optical properties with high contrast.

The first bulk electron-transfer photochromic compound with intrinsic second-order nonlinear optical (NLO) photoswitching properties has been synthesized. This system employs an electron-transfer photoactive asymmetric viologen ligand coordinated to a zinc(II) center.

A room-temperature X-ray-induced photochromic material for X-ray detection.

A color change: X-ray-induced photochromic species are rare and can be used for detection of X-rays. A highly robust X-ray-sensitive material with the discrete structure of a metal-organic complex has been found to show both soft and hard X-ray-induced photochromism at room temperature. A new ligand-to-ligand electron-transfer mechanism was proposed to elucidate this photochromic phenomenon.

A direct white-light-emitting metal-organic framework with tunable yellow-to-white photoluminescence by variation of excitation light.

A direct white-light metal-organic framework (MOF), [AgL](n) x nH(2)O (1, L = 4-cyanobenzoate), obtained by the reaction of deprotonated 4-cyanobenzoic acid and AgNO(3) in water, was found to exhibit tunable yellow-to-white photoluminescence by variation of excitation light. Interestingly, the close pure white emission of 1 has CIE-1931 chromaticity coordinates of (0.33, 0.34) when excited by 349-nm UV light, which is compatible to the light output of the deep UV LED.

A facile approach to hexanary chalcogenoborate featuring a 3-D chiral honeycomb-like open-framework constructed from rare-earth consolidating thiogallate-closo-dodecaborate.

A novel chiral open-framework structural hexanary chalcogenoborate, (K(3)I)[SmB(12)(GaS(4))(3)] (1), was obtained by a facile approach using boron as the reducing reagent; it shows weak SHG-activity and is transparent in the mid-IR region.

Synthesis, crystal and band structures, and properties of a new mixed three-dimensional framework metal pnictidehalide semiconductor, (Hg6Sb4)(CdI6).

A new, quaternary mercury and cadmium pnictidehalide semiconductor (Hg6Sb4)(CdI6) (1) has been prepared by the solid-state reaction and structurally characterized by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the space group R-3c of the rhombohedral system with four formula units in a cell: a=13.3818(9) A, alpha=90.93 degrees, and V=2395.3(3) A3. The crystal structural novelty of 1 derives from the fact that a 3-D mercury antimonide cationic network interpenetrates with an unusual 3-D cadmium iodide octahedral anionic network through the weak covalent interactions between mercury and iodine atoms to form a mixed 3-D framework. Among them, the cationic moiety features a perovskite-like 3-D network while the anionic moiety is characterized by a 3-D I6 octahedral anionic network with two-thirds I6 octahedra being occupied by Cd atoms. The optical properties were investigated in terms of the diffuse reflectance and Fourier transform infrared spectra. The electronic band structure along with density of states calculated by the density functional theory method indicates that compound 1 is a semiconductor with a direct band gap and that the optical absorption of 1 is mainly ascribed to the charge transitions from I-5p and Sb-5p states to Cd-5s and Hg-6s states.

Self-assembly and characterization of cyano-bridged bimetallic [Ln-Fe] and [Ln-Co] complexes (Ln = La, Pr, Nd and Sm). Nature of the magnetic interactions between the Ln(3+) and Fe(3+) ions.

Two structural series, including seven isomorphous heterodinuclear complexes, [Ln(DMSO)4(H2O)3(mu-CN)M(CN)5].H2O ([La-Fe] (1), [Pr-Fe] (2), [Pr-Co] (3), [Nd-Fe] (4), [Nd-Co] (5), [Sm-Fe] (6) and [Sm-Co] (7)), and seven isostructural 2-D stair-like cyano-bridged bimetallic assemblies, [Ln(DMSO)2(H2O)(mu-CN)4M(CN)2]n ([La-Fe]n (8), [Pr-Fe]n (9), [Pr-Co]n (10), [Nd-Fe]n (11), [Nd-Co]n (12), [Sm-Fe]n (13) and [Sm-Co]n (14)) (DMSO = dimethylsulfoxide), have been rationally prepared by a facile approach, a ball-milling method, and characterized by X-ray diffraction and magnetic measurements. The isomorphous structures, in conjunction with the diamagnetism of the Co(3+) and La(3+) ions, allow an approximation to the nature of coupling between the iron(III) and lanthanide(III) ions in the Ln(3+)-Fe(3+) complexes. The Ln(3+)-Fe(3+) interaction is ferromagnetic for the dinuclear [Pr-Fe] (2), [Nd-Fe] (4), and [Sm-Fe] (6) systems and for the 2-D [Pr-Fe]n (9), [Nd-Fe]n (11), and [Sm-Fe]n (13) assemblies.

catena-Poly[[[tetra-aqua-samarium(III)]-di-µ-isonicotinato-κO:O'] chloride].

In the structure of the title compound, {[Sm(C(6)H(4)NO(2))(2)(H(2)O)(4)]Cl}(n), the unique Sm(III) atom lies on a crystallographic twofold axis and is eight-coordinated by four O atoms from four isonicotinate ligands and four water mol-ecules in a slightly distorted square-anti-prismatic coodination environment. The Sm(III) atoms are bridged by two carboxyl-ate groups of two isonicotinate ligands, forming an extended chain along the c-axis direction. These chains are cross-linked through hydrogen bonds, forming a three-dimensional framework, with channels which accommodate the chloride anions.

A new type of hybrid magnetic semiconductor based upon polymeric iodoplumbate and metal-organic complexes as templates.

A new type of one-dimensional organic-inorganic hybrid [M(en)3]Pb2I6 [M = Mn (1), Fe (2), Zn (3), Ni (4); en = ethylenediamine] has been obtained and structurally characterized by X-ray crystallography, which opens a new approach to construct hybrid magnetic semiconductors. The results of optical absorption spectra and theoretical calculations for compounds 1-3 reveal a quantum confinement effect, and the variable-temperature magnetic susceptibility measurements for 1, 2, and 4 indicate ferromagnetic, antiferromagnetic, and paramagnetic behavior, respectively.