Biodegradable rare earth fluorochloride nanocrystals for phototheranostics

Rare earth (RE) doped inorganic nanocrystals have been demonstrated as efficient contrast agents for deep tissue shortwave-infrared (SWIR) imaging with high sensitivities leading to potential early detection of tumors. However, a potential concern is the unknown long-term toxicity and incompatibility of inorganic nanocrystals. In this work, biodegradable rare earth nanocrystals of Nd doped SrFCl coated with polydopamine (SrFCl:Nd@PDA) were designed. Instead of traditional fluoride hosts, the chlorinated SrF₂ (i.e. SrFCl) with low phonon energy which significantly improved the brightness of SrFCl:Nd in the SWIR region was used as the host. After coating with a NIR-absorptive PDA layer, the SrFCl:Nd nanoparticles serve as not only a contrast agent for photoacoustic imaging, but also a potential photothermal agent for cancer therapy. Moreover, these SrFCl:Nd@PDA nanoparticles can be rapidly and completely degraded in phosphate buffer solution within 1 h, which effectively addresses the concerns of the deleterious effects arising from potential long term accumulation. The increased accumulation and retention at tumor sites, and complete in vivo clearance ∼6 h after injection make these SrFCl:Nd@PDA nanoparticles a promising degradable phototheranostic agent.

Ln-CPs constructed from unsymmetrical tetracarboxylic acid ligand: Tunable white-light emission and highly sensitive detection of CrO42-, Cr2O72-, MnO4- in water

A series of isostructural lanthanide coordination polymers (Ln-CPs), [Ln(Hbptc)(H₂O)₄]·H₂O [Ln = Er (1), Pr (2), Dy (3), Sm (4), Gd (5), Nd (6) and Tb(7); H₄bptc = 2,3,3',4'-biphenyl tetracarboxylic acid] have been isolated based on an unsymmetrical tetracarboxylic acid. Single-crystal X-ray diffraction analysis reveals that all CPs featured a two dimensional (2D) layer with (6, 6, 6)-connected 6³ topology. Luminescent spectra demonstrate that CPs 1-7 exhibit impressive UV-visible luminescence in the solid state at room temperature. More significantly, a single-component white-light material with International Commission on Illumination (CIE) coordinates of (0.335, 0.334) for 4 (Sm-CP), very closing to the pure white-light of (0.333, 0.333) was obtained by finely tuning of the excitation wavelength. In addition, the luminescent detection for anions of 7 is investigated. Fluorescence measurements show that 7 can detect oxoanion pollutants Cr₂O₇^2-, CrO₄^2-, and MnO₄^- anions in aqueous solutions with high selectivity and sensitivity, which suggests that the Tb-CP is a promising functional luminescence probe for toxic oxoanions. The possible mechanisms of the quenching effect were also discussed in detail.

Two-Dimensional CoII Coordination Polymer for Photodegradation of Organic Dyes and Treatment of Temporary Osteoporosis of the Hip (TOH) by Regulating wnt/β-catenin/PPARγ Pathway

In this study, a new two-dimensional CoII-containing coordination polymer [Co(pda)(H2O)](DMF)2 (1, DMF=N,N-dimethylformamide) based on a light-harvesting triphenylamine type organic ligand has been successfully prepared by reaction of Co(NO3)2⋯6H2O and 4,4′-(phenylazanediyl)dibenzoic acid (H2pda) in a mixed solvent of water and DMF. Complex 1 has significant photocatalytic activity under visible light for the degradation of organic dyes such as rhodamine B (RhB), methylene blue (MB), as well as methyl orange (MO) assisted by H2O2. Compound 1 was investigated for anti-osteoporosis activity, the Annexin V-FITC/PI method was used to test the relationship between apoptosis and osteoporosis and the effect of 1 on bone marrow stem cell (BMSC) apoptosis. The expression levels of wnt/β, catenin, and PPARγ after treatment with 1 was determined by reverse transcription quantitative polymerase chain reaction. The DNA cleavage ability of 1 was further studied by molecular docking.

Luminescent metal–organic framework-based phosphor for the detection of toxic oxoanions in an aqueous medium

Compound 1 has been utilized for the luminescence based visible detection of chromate, permanganate and phosphate ions in aqueous medium.

Lanthanide complexes based on a conjugated pyridine carboxylate ligand: structures, luminescence and magnetic properties

Three lanthanide compounds have been synthesized, namely, {[Dy₂(bpda)₃(H₂O)₃]₄·2H₂O}(Dy-1), {[Sm(bpda)₂·(H₂O)]·H₂O}_n (Sm-2) and {[Tb₂(bpda)₃(H₂O)₃]₄·2H₂O} (Tb-3) (H₂bpda = 2,2′-bipyridine-6,6′-dicarboxylic acid). Their structures were determined by single crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy and thermogravimetric analysis. Dy-1 and Tb-3 are isostructural with a conjugate bimolecular four-nuclear cluster structure constructed with intramolecular hydrogen bonds and they form a 3D supramolecular structure with intermolecular hydrogen bonding. Sm-2 is a one-dimensional chain structure and is further connected by intricate hydrogen bonds into a three-dimensional supramolecular structure. These three compounds exhibit significant characteristic luminescence from the ligand to the central Ln(iii) ion, which is found by solid-state photoluminescence measurement. Sm-2 exhibits a long luminescence lifetime and high fluorescence quantum yield. A slow relaxation phenomenon is observed for the dysprosium compound by measuring the alternating-current susceptibility at low temperature and the underlying mechanism was further confirmed by theoretical calculations.

The structures, fluorescence and magnetic properties of series three lanthanide complexes have been investigated. Dysprosium complex exhibit the single-molecule behavior.

A Luminescent Amine-Functionalized Metal-Organic Framework Conjugated with Folic Acid as a Targeted Biocompatible pH-Responsive Nanocarrier for Apoptosis Induction in Breast Cancer Cells

Folic acid amine-functionalized metal-organic framework (FOLA@NH₂-Eu:TMU-62) with luminescent properties loaded with 5-fluorouracil (5-Fu), as an anticancer medication, was used to construct a new cancer targeted drug delivery system in the present study. The 5-Fu release from this targeted carrier along with MTT assay and trypan blue dye exclusion test results also exhibited pH-controlled characteristics of the given carrier in acidic environments, which is very suitable for targeting solid tumors. Then, the inhibitory action of 5-Fu-loaded FOLA@NH₂-Eu:TMU-62 for Michigan Cancer Foundation-7 (MCF7) cell migration was explored according to scratch wound healing assays. Based on the results, the FOLA@NH₂-Eu:TMU-62 carrier was not toxic for MCF-10A normal cells, but it was significantly toxic for MCF-7 breast cancer ones, revealing that the FOLA@NH₂-Eu:TMU-62 carrier could be utilized in accurate cancer treatments through apoptotic pathways with higher reactive oxygen species compared with 5-Fu alone. This cancer-targeted design of FOLA@NH₂-Eu:TMU-62 could thus pave the way for synergistic effects of targeting as well as organized release capabilities.

Photocatalytic and Ferric Ion Sensing Properties of a New Three-Dimensional Metal-Organic Framework Based on Cuboctahedral Secondary Building Units

A new three-dimensional microporous metal-organic framework based on Zn(II) clusters with the formula {[Zn₇(NDC)_5.5(μ₄-OH)₃]·7DMF} _n (1) (H₂NDC = 1,4-naphthalenedicarboxylic acid) had been synthesized and characterized. The MOF 1 displays an uncommon bsn topology, which is based on a unique heptanuclear Zn₇(OH)₃(CO₂)₁₁ cluster as a secondary building unit. The MOF had been employed as a photocatalyst for the photodegradation of model organic dyes rhodamine B and methyl violet in light. The results of photocatalytic experiments showed that 1 can successfully be employed as the photocatalyst for the benign decomposition of these dyes. A mechanism for the photcatalysis exhibited by 1 had been proposed using the results of density of states (DOS) and partial DOS calculations. The fluorescence properties of the MOF have been investigated, which revealed that 1 could be exploited as the luminescent sensor to recognize Fe³⁺ ions with perceptible quenching (K _sv = 6.55 × 10⁴ M-¹) and a limit of detection of 1.16 ppm.

Temperature tuned syntheses of two new d10-based Cd(ii) cluster metal–organic frameworks: luminescence sensing and photocatalytic properties

The solvothermal reactions of 5,5′-(1,4-phenylenebis(methyleneoxy))diisophthalic acid (H₄L) and the N-donor ancillary ligand 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (bpz) with cadmium(ii) salts at two different reaction temperatures yielded two new metal–organic frameworks (MOFs), viz., [Cd(H₂L)(bpz)]_n (1) and [Cd₂(H₄L)(L)(bpz)₂]_n (2), which have been characterized by FTIR and single crystal X-ray diffraction. The single crystal X-ray diffraction studies revealed that 1 displays a 3-periodic network with monometallic SBU, while 2 exhibits a 3-periodic network with a 2-fold interpenetration feature. The effects of variation in reaction temperature on the architecture of MOFs 1 and 2 have been discussed. The luminescence investigation indicates that both 1 and 2 displayed good turn-off luminescence sensing against nitroaromatic compounds (NACs), especially m-nitrophenol (MNP), via a decrease in their luminescence intensities with a K_sv value of 6.43 × 10³ for 1 and 2.03 × 10⁴ for 2 and LOD values of 1.09 and 0.81 ppm for 1 and 2, respectively. The plausible mechanism for the decline in luminescence intensity of the MOFs with NACs has been addressed using theoretical calculations. The photocatalytic properties for both the MOFs demonstrated that they display efficient photocatalytic performances to degrade methyl violet (MV) under UV irradiation. The plausible mechanism through which these MOFs exhibited photocatalytic properties has been suggested using band gap calculations.

Two new d¹⁰-based Cd(ii) MOFs were synthesized and their photoluminescence sensing to selectively detect m-nitrophenol (MNP) and ability to decompose the organic dye methyl violet (MV) were explored.

Syntheses and crystal structures of new dinuclear lanthanide complexes based on 3-(4-hydroxyphenyl)propanoic acid: Hirshfeld surface analyses and photoluminescence sensing

A series of ten new lanthanide complexes, [Ln₂(HPA)₆(bipy)₂·4H₂O·2bipy], were synthesized and their photoluminescence sensing and Hirshfeld surface analyses performed.

Structural diversity, magnetic properties, and luminescence sensing of five 3D coordination polymers derived from designed 3,5-di(2′,4′-dicarboxylphenyl)benozoic acid

Five 3D CPs were constructed from a designed π-conjugated aromatic pentacarboxylate with diverse structures.

Two luminescent lanthanide–organic frameworks containing bithiophene groups for the selective detection of nitrobenzene and Fe3+

Two isostructural lanthanide–organic frameworks containing bithiophene groups can be used as fast-response fluorescent probes for the sensitive detection of nitrobenzene and Fe³⁺ ions through fluorescence quenching.

Mechanochemical and Conventional Synthesis of Zn(II)/Cd(II) Luminescent Coordination Polymers: Dual Sensing Probe for Selective Detection of Chromate Anions and TNP in Aqueous Phase

Isostructural Zn(II)/Cd(II) mixed ligand coordination polymers (CPs) {[M(IPA)(L)]}_n (CP1 and CP2) built from isophthalic acid (H₂IPA) and 3-pyridylcarboxaldehyde nicotinoylhydrazone (L) were prepared using versatile synthetic routes: viz., diffusion of precursor solutions, conventional reflux methods, and green mechanochemical (grinding) reactions. Both robust CPs synthesized by different routes were characterized by various analytical methods, and their thermal and chemical stability as well as the phase purity was established. Crystallographic studies revealed that CP1 and CP2 are isostructural frameworks and feature a double-lined two-dimensional network composed of Zn²⁺/Cd²⁺ nodes connected through IPA and pillared by the Schiff base ligand L with a double-walled edge. The photoluminescent (PL) properties of CP1 and CP2 have been exploited as dual detection fluorosensors for hexavalent chromate anions (CrO₄^2-/Cr₂O₇^2-) and 2,4,6-trinitrophenol (TNP) because it was observed that the emission intensity of aqueous suspensions of CPs selectively quenches by chromate anions or TNP among large pools of different anions or nitro compounds, respectively. Competitive experiments in the presence of interfering anions/other nitro compounds also revealed no major effect in the quenching efficiency, suggesting the selective detection of hexavalent chromate anions as well as TNP by the LCPs. The limits of detection by CP1 for CrO₄^2-/Cr₂O₇^2- and TNP are 4 ppm/4 ppm and 28 ppb, respectively, whereas the limits of detection by CP2 for the same analytes are 1 ppm/1 ppm and 14 ppb, respectively. A probable mechanism for the quenching phenomena is also discussed.

Self-assembly of new M(ii) coordination polymers based on asymmetric 1,3,4-oxadiazole-containing ligands: effect of counterions and magnetic properties

A construction strategy of high dimensional porous coordination polymers has been investigated based on two unsymmetrical ligands and “naked” and coordinated metal ions.

Solvothermal self-assembly of Cd2+ coordination polymers with supramolecular networks involving N-donor ligands and aromatic dicarboxylates: synthesis, crystal structure and photoluminescence studies

Structural, solid state luminescence of Cd(ii) coordination polymers and detection of acetone by CP1via luminescence quenching have been discussed.

Crystal structure of poly-[triaqua-(μ3-3,4,5,6-tetrafluoro-1,2-phthalato-κ4 O:O′:O′′,O′′′) (2,3,4,5-tetrafluoro-benzoato-κ2 O,O′) praseodymium(III)], C15H7F8O9Pr

C15H7F8O9Pr, monoclinic, P21/n (no. 14), a = 6.2167(3) Å, b = 9.7769(5) Å, c = 29.6562(15) Å, β = 93.2916(8)°, V = 1799.53 Å3, Z = 4, R gt(F) = 0.0317, wR ref(F 2) = 0.0729, T = 293(2) K.