Two Amino-Decorated Metal–Organic Frameworks for Highly Selective and Quantitatively Sensing of Hg^II and Cr^VI in Aqueous Solution

Two amino-decorated metal–organic frameworks have been constructed, which are the rare examples of MOF-based fluorescent probes targeting environmentally relevant guest species, such as Hg (II) and Cr (VI) ions in aqueous solution, with high selectivity and sensitivity. The possible sensing mechanism is also discussed

Two Amino-Decorated Metal–Organic Frameworks for Highly Selective and Quantitatively Sensing of Hg^II and Cr^VI in Aqueous Solution

Two amino-decorated metal–organic frameworks have been constructed, which are the rare examples of MOF-based fluorescent probes targeting environmentally relevant guest species, such as Hg (II) and Cr (VI) ions in aqueous solution, with high selectivity and sensitivity. The possible sensing mechanism is also discussed

Protein Aggregation and Performance Optimization Based on Microconformational Changes of Aromatic Hydrophobic Regions

Protein aggregation is a key concern in biopharmaceutical development and manufacturing. There is growing interest in understanding how the changes in protein microconformation affect the aggregation behavior. This study selected several representative proteins and first manipulated microconformational changes of the aromatic hydrophobic regions of proteins, especially tryptophan residues, by using amine or guanidine additives. The effects of the interactions between the additives and proteins on the aromatic hydrophobic regions could be grouped into three categories: exposure to solvent, burial into core, and no change. The microconformational parameters of the tryptophan residue, including fluorescence peak position (λ_m), degree of hydrolysis, solvent accessible surface area (<i>SAS</i>), and packing density (<i>Den</i>), were obtained by steady-state fluorescence spectroscopy, proteolysis coupled with electrophoresis, and molecular dynamics simulation. Furthermore, the aggregation degrees of globular proteins with distinct surface aromatic hydrophobilities under mechanical stress were investigated. A strong correlation was observed between protein aggregation and the microconformational changes of the aromatic hydrophobic regions incurred by amine or guanidine additives. Protein aggregation was enhanced when the aromatic hydrophobic regions were exposed to the solvent but suppressed when the additives led to burial of the aromatic hydrophobic regions with lower-polarity microenvironment. These findings shed light on the relationship between protein aggregation and molecular conformation and paved way for future preformulation studies of therapeutic proteins

Metal–Organic Frameworks Constructed from a New Thiophene-Functionalized Dicarboxylate: Luminescence Sensing and Pesticide Removal

A family of thiophene-based metal–organic frameworks (MOFs), [Zn­(L)­(BBI)·(H₂O)₂] (<b>1</b>) (BBI = 1,1′-(1,4-butanediyl)­bis­(imidazole)) and [Cd­(L)­(TPOM)_0.75]·<i>x</i>S (<b>2</b>) (TPOM = tetrakis­(4-pyridyloxy-methylene) methane, S represents noncoordinated solvent molecules) was constructed by employing a new linear thiophene-functionalized dicarboxylic acid (benzo-(1,2;4,5)-bis­(thiophene-2′-carboxylic acid, H₂L) to assemble with d¹⁰ ions in the presence of a flexible ancillary ligand under solvothermal conditions, which exhibit diverse structures. Most strikingly, both compounds <b>1</b> and <b>2</b> could be efficient luminescent sensory materials that are highly selective and sensitive to environmental contaminants, especially for Hg­(II), Cu­(II), Cr­(VI), and salicylaldehyde, and yet remain unaffected by other molecules that may coexit. Furthermore, this is the first report on MOF-based sensors capable of recyclable detection of Hg­(II), Cr­(VI), and salicylaldehyde so far. The luminescent sensing mechanism was studied in detail as well. In addition, compound <b>2</b> is one of the rare examples of high-performance MOFs trapping 2,4-dichlorophenol from the wasted methanol solution

Metal–Organic Frameworks Constructed from a New Thiophene-Functionalized Dicarboxylate: Luminescence Sensing and Pesticide Removal

A family of thiophene-based metal–organic frameworks (MOFs), [Zn­(L)­(BBI)·(H₂O)₂] (<b>1</b>) (BBI = 1,1′-(1,4-butanediyl)­bis­(imidazole)) and [Cd­(L)­(TPOM)_0.75]·<i>x</i>S (<b>2</b>) (TPOM = tetrakis­(4-pyridyloxy-methylene) methane, S represents noncoordinated solvent molecules) was constructed by employing a new linear thiophene-functionalized dicarboxylic acid (benzo-(1,2;4,5)-bis­(thiophene-2′-carboxylic acid, H₂L) to assemble with d¹⁰ ions in the presence of a flexible ancillary ligand under solvothermal conditions, which exhibit diverse structures. Most strikingly, both compounds <b>1</b> and <b>2</b> could be efficient luminescent sensory materials that are highly selective and sensitive to environmental contaminants, especially for Hg­(II), Cu­(II), Cr­(VI), and salicylaldehyde, and yet remain unaffected by other molecules that may coexit. Furthermore, this is the first report on MOF-based sensors capable of recyclable detection of Hg­(II), Cr­(VI), and salicylaldehyde so far. The luminescent sensing mechanism was studied in detail as well. In addition, compound <b>2</b> is one of the rare examples of high-performance MOFs trapping 2,4-dichlorophenol from the wasted methanol solution

Assembly of Two Porous Cadmium(II) Frameworks: Selective Adsorption and Luminescent Property

Two microporous cadmium­(II) metal–organic frameworks, [Cd­(cptpy)­(Ac)­(H₂O)·(DMA)­(H₂O)]_<i>n</i> (<b>1</b>) and [Cd­(cptpy)₂·(DMF)₂]_<i>n</i> (<b>2</b>) (Hcptpy = 4-(4-carboxyphenyl)-2,2′:4′,4″-terpyridine, DMA = <i>N</i>,<i>N</i>-dimethylacetamide, DMF = dimethylformamide) have been solvothermally synthesized under different reaction conditions. Complex <b>1</b> is a double-interpenetrating 3D network, while <b>2</b> is a noninterpenetrating (3,5)-connected 2D framework. The dehydrated forms of compounds <b>1</b> and <b>2</b> exhibit selective adsorption of CO₂ over N₂ and H₂O over CH₃OH. In addition, the adsorption value of CO₂ for <b>2</b> is higher than that of <b>1.</b> The contents of uncoordinated pyridine nitrogen (Lewis basic sites) per formula unit of <b>1</b> and <b>2</b> are 2.16 and 4.36%, respectively. Obviously, the grafting of more uncoordinated pyridine nitrogen into compound <b>2</b> could enhance adsorption of the acidic CO₂ molecule. Notably, both <b>1</b> and <b>2</b> display strong photoluminescence. The nature of electronic transitions for complex <b>1</b> in the photoluminescent process was investigated by means of time-dependent density functional theory (TDDFT) calculations and molecular orbital analyses, which collaborates that the luminescent property is ligand-based

Assembly of Two Porous Cadmium(II) Frameworks: Selective Adsorption and Luminescent Property

Two microporous cadmium­(II) metal–organic frameworks, [Cd­(cptpy)­(Ac)­(H₂O)·(DMA)­(H₂O)]_<i>n</i> (<b>1</b>) and [Cd­(cptpy)₂·(DMF)₂]_<i>n</i> (<b>2</b>) (Hcptpy = 4-(4-carboxyphenyl)-2,2′:4′,4″-terpyridine, DMA = <i>N</i>,<i>N</i>-dimethylacetamide, DMF = dimethylformamide) have been solvothermally synthesized under different reaction conditions. Complex <b>1</b> is a double-interpenetrating 3D network, while <b>2</b> is a noninterpenetrating (3,5)-connected 2D framework. The dehydrated forms of compounds <b>1</b> and <b>2</b> exhibit selective adsorption of CO₂ over N₂ and H₂O over CH₃OH. In addition, the adsorption value of CO₂ for <b>2</b> is higher than that of <b>1.</b> The contents of uncoordinated pyridine nitrogen (Lewis basic sites) per formula unit of <b>1</b> and <b>2</b> are 2.16 and 4.36%, respectively. Obviously, the grafting of more uncoordinated pyridine nitrogen into compound <b>2</b> could enhance adsorption of the acidic CO₂ molecule. Notably, both <b>1</b> and <b>2</b> display strong photoluminescence. The nature of electronic transitions for complex <b>1</b> in the photoluminescent process was investigated by means of time-dependent density functional theory (TDDFT) calculations and molecular orbital analyses, which collaborates that the luminescent property is ligand-based

Two Copper(II) Metal–Organic Frameworks with Nanoporous Channels and Vacant Coordination Sites

Two three-dimensional microporous compounds, Cu₆(BTTC)₄­(H₂O)₆·<i>x</i>S (<b>1</b>) and [(CH₃)₂NH₂]₃­[(Cu₄Cl)₃­(BTTC)₈]·<i>y</i>S (<b>2</b>, H₃BTTC = benzo-(1,2;3,4;5,6)-tris (thiophene-2′-carboxylic acid), S represents noncoordinated solvent molecules), have been solvothermally synthesized and characterized, both of which are based upon truncated octahedron subunits and contain uniform nanosized cavities but exhibit different topological frameworks. Complex <b>1</b> demonstrates high adsorption enthalpies for H₂ and CO₂ gas molecules, stemming principally from the presence of the exposed metal Cu­(II) sites on the pore surface. In particular, activated complex <b>1</b> shows high efficiency for the separation of energy-correlated molecules, including CO₂ over N₂ and CH₄ under ambient conditions

Metal–Organic Frameworks Constructed from d‑Camphor Acid: Bifunctional Properties Related to Luminescence Sensing and Liquid-Phase Separation

Three metal–organic frameworks (MOFs) [M₂(d-cam)₂(bimb)₂]_<i>n</i>·3.5<i>n</i>H₂O (M = Mn for <b>1</b>, Co for <b>2</b>) and [Cd₈(d-cam)₈(bimb)₄]_<i>n</i> (<b>3</b>) (d-H₂cam = d-camphor acid, bimb = 4,4′-bis­(1-imidazolyl)­biphenyl), solvothermally synthesized, exhibit structural diversity. The charming aspect of these frameworks is that compound <b>3</b> is the very first MOF-based sensor for quantitatively detecting three different types of analytes (metal ions, aromatic molecules, and pesticides). And also, both compounds <b>2</b> and <b>3</b> show rapid uptake and ready regeneration for methyl orange (MO) and can selectively bind MO over methylene blue (MB) with high MO/MB separation ratio

Highly Selective Gaseous and Liquid-Phase Separation over a Novel Cobalt(II) Metal–Organic Framework

The mild recognition sites of oxygen atoms and phenyl rings from 5-(4-pyridyl)-methoxyl isophthalic acid (5,4-PMIA^2–) moieties and tetrakis­(4-pyridyloxymethylene) methane (TPOM) linkers inside the channels of a novel three-dimensional microporous metal–organic framework (MOF) [Co₂(5,4-PMIA)₂(TPOM)_0.5]·<i>x</i>solvent (<b>1</b>) are presumed to provide pore environments with moderate contacts toward guests, as indicated by grand canonical Monte Carlo simulations, which appear to be beneficial for adsorption and separation applications. As expected, <b>1</b> represents one of the rare examples that show both high storage capacity of C₂H_<i>n</i> and good adsorption selectivity of C₂H_<i>n</i>/CH₄ and CO₂/CH₄ under ambient conditions, and yet, it has significantly lower energy consumption for regeneration. In addition, a validated submicro-<b>1</b>-based microsolid-phase extraction (μ-SPE) method for the determination of trace monohydroxylated polycyclic aromatic hydrocarbons in complex human urine was developed with satisfactory sensitivity and good precision by online coupling to liquid chromatography-mass spectrometry, which represents the first example of a mixed-ligand MOF applied as an efficient sorbent for μ-SPE