Dopant effect on the optical and thermal properties of the 2D organic-inorganic hybrid perovskite (HDA)2PbBr4.

Lead-based two-dimensional organic-inorganic hybrid perovskites (2D HOIPs) are popular materials with various optical properties, which can be tuned through metal ion doping. Due to the size and valence misfit, metal ion dopants in 2D lead-based HOIPs are still limited. In this work, Mn2+, Sb3+ and Bi3+ are doped into 2D (HDA)2PbBr4 (HDA = protonated dopamine) successfully. As a result, the dopants in 2D (HDA)2PbBr4 can induce their characteristic optical spectra, which is studied at different temperatures and excitation powers. The temperature-dependent energy transfer in the Mn-doped sample has been clarified, in which abnormal phenomena including negative thermal quenching have been observed. In addition, the dopant ions can impact the phase transition temperatures of the samples, especially lowering their crystallization temperatures greatly. The mussel-inspired organic cation, feasible metal ion regulation, and superior stability provide (HDA)2PbBr4 potential for further applications.

Multi-Mode Photoluminescence Regulation in a Zero-Dimensional Organic-Inorganic Hybrid Metal Halide Perovskite─[(CH3)4N]2SnCl6.

Metal ion-doped zero-dimensional halide perovskites provide good platforms to generate broadband emission and explore the fundamental dynamics of emission regulations. Recently, Sb3+-doped zero-dimensional halide perovskites have attracted considerable attention for the high quantum yield of yellow emission; however, the triplet state recombination is activated and the singlet state emission is usually absent. Herein, we fabricate an Sb3+-doped zero-dimensional [(CH3)4N]2SnCl6 perovskite that can induce singlet and triplet emission. Density functional theory calculation shows that there are some overlaps between the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals, which may induce a large energy separation between the lowest excited triplet states (T1) and the lowest excited singlet states (S1) [ΔE(S1 - T1)], impeding all the carriers' transfer from the singlet state to the triplet state. As a result, the reserved singlet emission together with the triplet emission can be regulated by excitation wavelength in situ. In addition, different Bi3+ ratios are co-doped into Sb3+@[(CH3)4N]2SnCl6, resulting in a photoluminescence ex situ regulation. Single-phase white light LED and optical anti-counterfeiting are developed further.

Single-photon upconversion in 6-pentaceneone crystal from bulk to ultrathin flakes.

Phonon-assisted single-photon upconversion, which was not previously reported in organic materials, has been demonstrated in the 6-pentaceneone crystal through the linear pumping power dependent anti-Stokes photoluminescence (ASPL), nanoseconds PL lifetime and quenched ASPL at low temperature. Furthermore, the 6-pentaceneone crystal can be mechanically exfoliated to ultrathin flakes and it exhibits thickness-dependent photoluminescence.

Efficient Removal of [UO2]2+, Cs+, and Sr2+ Ions by Radiation-Resistant Gallium Thioantimonates.

Unconventional ion exchangers can achieve efficient removal of [UO2]2+, Cs+, and Sr2+ ions from complex aqueous solutions and are of great interest for environmental remediation. We report two new gallium thioantimonates, [Me2NH2]2[Ga2Sb2S7]·H2O (FJSM-GAS-1) and [Et2NH2]2[Ga2Sb2S7]·H2O (FJSM-GAS-2), which present excellent ion exchange properties for [UO2]2+, Cs+, and Sr2+ ions. They exhibit high ion exchange capacities for [UO2]2+, Cs+, and Sr2+ ions ( qmU = 196 mg/g, qmCs = 164 mg/g, and qmSr = 80 mg/g for FJSM-GAS-1, qmU = 144 mg/g for FJSM-GAS-2) and short equilibrium times for [UO2]2+ ion exchange (5 min for FJSM-GAS-1 and 15 min for FJSM-GAS-2, respectively). Both compounds display active ion exchange with [UO2]2+ in the pH range of 2.9-10.5. Moreover, the sulfide compounds could maintain high distribution coefficients KdU even in the presence of excess Na+, Ca2+, and HCO3-. The distribution coefficient KdU of 6.06 × 106 mL/g exhibited by FJSM-GAS-1 is the highest among the reported U adsorbents. The [UO2]2+-laden products can be recycled by conveniently eluting the uranium with a low-cost method. These advantages combined with facile synthesis, as well as ß and γ radiation resistance, make FJSM-GAS-1 and FJSM-GAS-2 promising for selective separations in nuclear waste remediation.

Layered A2Sn3S7·1.25H2O (A = Organic Cation) as Efficient Ion-Exchanger for Rare Earth Element Recovery.

Exploring new ion-exchangers for the recovery of rare earth elements (REEs) and recycling is worthwhile for the high-tech industry and an eco-friendly sustainable economy. The efficient enrichment of low concentration REE from complex aqueous solutions containing large excess of competitive ions is challenging. Here we present a chalcogenide example as a superior REE ion-exchanger efficiently removing them from very complex aqueous solutions, (Me2NH2)1.33(Me3NH)0.67 Sn3S7·1.25H2O (FJSM-SnS). The material exhibits fast and efficient ion exchange behavior with short equilibrium time (<5 min), high adsorption capacity (139 mg/g for Eu, 147 mg/g for Tb, 126 mg/g for Nd), wide pH resistance (1.9-8.5), the largest distribution coefficient (Kd) value of 6.5 × 106 mL/g, good selectivity against Al3+, Fe3+, and Na+ ions, and high recovery rate (>99%) at low concentrations. Moreover, after ion-exchange, the REE in corresponding exchanged products could be easily recovered by elution. FJSM-SnS has superior capacity and faster absorption kinetics than other states of the artificial REE sorbents such as Al2O3/EG, clay minerals, zeolite, and activated carbon.

Efficient Removal and Recovery of Uranium by a Layered Organic-Inorganic Hybrid Thiostannate.

Uranium is important in the nuclear fuel cycle both as an energy source and as radioactive waste. It is of vital importance to recover uranium from nuclear waste solutions for further treatment and disposal. Herein we present the first chalcogenide example, (Me2NH2)1.33(Me3NH)0.67Sn3S7·1.25H2O (FJSM-SnS), in which organic amine cations can be used for selective UO2(2+) ion-exchange. The UO2(2+)-exchange kinetics perfectly conforms to pseudo-second-order reaction, which is observed for the first time in a chalcogenide ion-exchanger. This reveals the chemical adsorption process and its ion-exchange mechanism. FJSM-SnS has excellent pH stability in both strongly acidic and basic environments (pH = 2.1-11), with a maximum uranium-exchange capacity of 338.43 mg/g. It can efficiently capture UO2(2+) ions in the presence of high concentrations of Na(+), Ca(2+), or HCO3(-) (the highest distribution coefficient Kd value reached 4.28 × 10(4) mL/g). The material is also very effective in removing of trace levels of U in the presence of excess Na(+) (the relative amounts of U removed are close to 100%). The UO2(2+)···S(2-) interactions are the basis for the high selectivity. Importantly, the uranyl ion in the exchanged products could be easily eluted with an environmentally friendly method, by treating the UO2(2+)-laden materials with a concentrated KCl solution. These advantages coupled with the very high loading capacity, low cost, environmentally friendly nature, and facile synthesis make FJSM-SnS a new promising remediation material for removal of radioactive U from nuclear waste solutions.

Synthesis, Structure, Band Gap, and Near-Infrared Photosensitivity of a New Chalcogenide Crystal, (NH4)4Ag12Sn7Se22.

A new chalcogenide crystal, (NH4)4Ag12Sn7Se22 (FJSM-STS), has been solvothermally synthesized. The crystal structure, which is composed of arrays of [Sn3Se9]n(6n-) chains interconnecting [SnAg6Se10]n(10n-) and [Ag3Se4]n(5n-) layers, is unprecedented among the reported A/Ag/Sn/Q (A = cation; Q = S, Se, and Te) compounds. Optical absorption together with theoretical calculations of the band structure indicate a direct band gap of 1.21 eV for FJSM-STS, which is close to the ideal band gap to maximize the photoconversion efficiency proposed by Shockley and Queisser. The toxic-metal-free crystal of FJSM-STS exhibits obvious photosensitivity in the near-infrared range. The variates of power and temperature on the photosensitivity have been studied.

Microwave-assisted ionothermal synthesis of a water-stable Eu-coordination polymer: a Ba(2+) ion detector and fluorescence thermometer.

A water-stable Eu-coordination polymer (CP), namely [HMIm]Eu(DHBDC)2 (1) (HMIm = 1-hexyl-3-methylimidazolium; H2DHBDC = 2,5-dihydroxytelephthalic acid), was obtained using ionothermal synthesis. 1 represents the first coordination polymer capable of qualitative and quantitative detection of Ba(2+) in aqueous solutions with a fluorescent enhancement that is visible to the human eye, which can be ascribed to the formation of fluorescent compound Ba(DHBDC) (2) during the detection process. Temperature-dependent photoluminescence (PL) makes 1 a potential material for a fluorescence thermometer. Furthermore, the detection process for Ba(2+) using 1 turns the one-PL transition fluorescence thermometer into a two-PL transition fluorescence thermometer, increasing the accuracy of the fluorescence thermometer.

Syntheses, Crystal Structures, Ion-Exchange, and Photocatalytic Properties of Two Amine-Directed Ge-Sb-S Compounds.

Among numerous heterometallic chalcogenidoantimonates, relatively a few amine-directed Ge-Sb-S compounds have been synthesized. Presented here are the solvothermal syntheses, crystal structures, and ion-exchange, optical, and photocatalytic properties of two novel amine-directed Ge-Sb-S compounds, namely, [CH3NH3]20Ge10Sb28S72·7H2O (1) and [(CH3CH2CH2)2NH2]3Ge3Sb5S15·0.5(C2H5OH) (2). The structure of 1 features an unprecedented two-dimensional Ge-Sb-S double-layer composed of two twofold rotational symmetry-related thick [Ge8Sb28S72]n(28n-) single layers adhered via vertex-sharing [GeS4] tetrahedra. Compound 2 features a unique [Ge3Sb5S15]n(3n-) slab perforated with large elliptic-like windows. Remarkably, compound 1 exhibited excellent Cs(+) ion-exchange property despite the presence of excess competitive cations, such as Na(+), K(+), Mg(2+), and Ca(2+) ions. In addition, compound 1 displayed visible-light-driven photocatalytic activity for degradation of rhodamine B.

A hybrid with uniaxial negative thermal expansion behaviour: the synergistic role of organic and inorganic components.

Presented is an inorganic-organic hybrid compound Mn2(api)Sb2S5 (1) with uniaxial NTE behaviour. The NTE of reflects a strong synergistic role of organic and inorganic components, which results from the novel zigzag linkage of interlamellar organic ligands. An "elevator-platform" expansion mechanism was proposed, with implications for future design of sensitive hybrid thermomechanical actuators.

[(Me)2NH2][BiGeS4]: the first organically directed bismuth thiogermanate with Rb+ ion exchange property.

The first organically directed bismuth thiogermanate, namely [(Me)2NH2][BiGeS4] (), has been solvothermally synthesized and characterized. The structure features a two-dimensional anionic network of [BiGeS4]n(n-), with dimethylammonium as a counterion and a structure-directing agent. is able to undergo ion exchange with Rb(+) ions.

(enH2)(4.5)[In(As(V)S4)3][As2(III)(µ-S2)S3]Cl and (enH2)MnAs(III)As(V)S6: two thioarsenates(III, V) with mixed-valent optical properties.

Two mixed-valent thioarsenates, namely (enH2)(4.5)[In(As(V)S4)3][As2(III)(µ-S2)S3]Cl (1) and (enH2)MnAs(III)As(V)S6 (2) (en = ethylenediamine), have been solvothermally synthesized and characterized. Thermal stability, magnetic and mixed-valent optical properties, as well as theoretical band structures and DOSs, of 1 and 2 have also been studied.