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The stability of metal organic frameworks (MOFs) in a water-rich environment is a topic of significant importance, especially for adsorption and water purification applications. MIL-88A containing iron ions and fumaric acid ligands, was synthesized through a water-based viable strategy. The robustness of MIL-88A in aqueous solutions was studied experimentally, through evaluating the chemical, thermal, and hydrolytic stability of this compound by varying the conditions and properties of aqueous solutions. Different characterization techniques were employed to explore the features of the synthesized MIL-88A such as XRD, SEM, FTIR, TGA, UV–vis DRS, zeta potential, and MP-AES measurements. The electronic structure was studied on a model nanocrystal with density functional theory (DFT) calculations. The MIL-88A structure was drastically affected in basic medium as confirmed by the characterization techniques used. MIL-88A became completely amorphous upon exposure to boiling water. The hydrolytic stability results showed that MIL-88A loses gradually its structural integrity in each water cycle.

The multi-channel crystals consisting of 2-D networks G@[M(NO3)2L] are an unusually efficient, tolerant, and reproducible matrix offering M-dependent adsorption/desorption of various guest molecules in the single-crystal-to-single-crystal mode.

Formation of the unexpected hexafluorosilicate (SiF62−) encapsulated cages constructed. Interestingly, this shows that the surface of glassware should be given serious consideration for long-duration reactions with active F-containing species.

Discrete cages or a 4-fold 3D network of Cu3L4 units were constructed depending on the metallophilicity of outside anions. Interestingly, the heterogeneous catalysis is much more effective than its corresponding homogeneous catalysis.

Self-assembly of Cd(NO3)2 with a new C2-symmetric multidentate N-donor ligand, N,N′-((1,1′-(anthracene-9,10-diylbis(methylene))bis(1H-1,2,3-triazole-4,1-diyl))bis(methylene))bis(1-(pyridin-3-yl)-N-...

Self-assembly of silver(I) perchlorate with a C3-symmetric tridentate N-donor ligand produces stable crystals with open channels via catenation of 1D ladder-type coordination polymers. The open-channel crystal shows both unprecedented mixture and temperature effects on the adsorption and separation of o-, m-, and p-xylene isomers in a single-crystal-to-single-crystal (SCSC) mode. o-Xylene is not adsorbed into the channel at 5 °C, but is inserted into the channel at room temperature. In particular, the 1 : 1 mixture of o- and m-xylene was adsorbed into the channel in the 1 : 1 mole ratio via intermolecular weak interactions at 5 °C. In addition, the porous crystals are a practical template for structural determination of small liquid hydrocarbons in the SCSC state.

Systematic supramolecular isomerism between metallacyclodimeric species and sinusoidal 1D coordination polymers was observed. Slow diffusion of AgX (X− = NO3−, BF4−, ClO4−, and PF6−) with 1,3-bis(dimethyl(pyridin-4-yl)silyl)propane afforded 28-membered metallacyclodimers [AgL]2(X)2 with argentophilic, electrostatic, and π–π interactions that are very sensitive to the bite size of each anion in the crystalline state. Successive anion exchange of [Ag(L)]2(NO3)2 with X− (X− = BF4−, ClO4−, and PF6−) crystallized in situ, resulting in a systematic supramolecular isomerization to sinusoidal 1D coordination polymers in mother liquor. In the following pages, the different photophysical properties between the metallacyclodimeric species and the sinusoidal 1D coordination polymers on some solvent adsorption are discussed based on the photoluminescence (PL) spectra.

Unusual successive two-step crystallization of a pair of chiral coordination polymers was carried out. Self-assembly of Zn(NO3)2 with a pair of chiral C3-symmetric tridentate N-donor ligands (1S,2R-L and 1R,2S-L) produces single crystals consisting of chiral enantiomeric 1D ladder coordination polymers, CH2Cl2∙2CH3CN@[Zn3(NO3)6(1S,2R-L)2] and CH2Cl2∙2CH3CN@[Zn3(NO3)6(1R,2S-L)2], after which the single crystals are transformed into new crystals in their hydrated forms, 2CH3CN@[Zn3(NO3)6(1S,2R-L)2(H2O)2] and 2CH3CN@[Zn3(NO3)6(1R,2S-L)2(H2O)2], respectively, under the moisture condition, in the single-crystal-to-single-crystal (SCSC) mode. The crystals consist of hexagonally packed chiral 1D coordination polymers in an enantiomeric arrangement, and their hydration shows a subtle difference depending on the chirality.

Self-assembly of Hg(ClO4)2 with a horse-shoe type ligand in acetone at room temperature produces single crystals consisting of [Hg4(ClO4)4(CH2COCH2)2L2]·CH3COCH3via straightforward formation of dianionic acetonylate −CH2COCH2− in high yields.

A procedure for the formation of a nitrate-encapsulating tripalladium(II) cage via self-assembly of Pd(NO3)2 with 1,3-bis(dimethyl(pyridin-4-yl)silyl)propane (L) was developed. The self-assembly reaction initially produces spiro-type macrocycles, PdL2, and finally results in transformation into a nitrate-encapsulated cage, [(NO3)@Pd3L6], in the mother liquor. The reaction of PdX2 (X− = BF4−, ClO4−, PF6−, and CF3SO3− instead of NO3−) with L gives rise to a spiro species, PdL2, as the final product, and anion exchange of the spiro products, [PdL2](X)2, with NO3− produces the tripalladium cage [(NO3)@Pd3L6].

Reaction of CdI2 with C2-symmetric multidentate N-donor (L) in a mixture of ethanol and dichloromethane produces single crystals of 3(dichloromethane)·2(ethanol)@[CdI2L] (23.26 Å thickness layer) with a new 2D topology of {43·62·8}. These single crystals in tetrahydrofuran are isomerized into new single crystals of 4(tetrahydrofuran)@[CdI2L] (9.15 Å thickness layer) with a 2D topology of sql {44·62}. The tetrahydrofuran solvate molecules of 4(tetrahydrofuran)[CdI2L] are fully replaced by adsorption of dihalomethane molecules in the single-crystal-to-single-crystal (SCSC) mode. The most interesting feature is that both 3(dichloromethane)·2(ethanol)@[CdI2L] and 4(tetrahydrofuran)@[CdI2L] crystals are integral to an efficient and tolerant matrix for recognition of diiodomethane (CH2I2) in the SCSC mode, even though the adsorption rate of 4(tetrahydrofuran)@[CdI2L] crystals is much faster than that of 3(dichloromethane)·2(ethanol)@[CdI2L]. That is, their blue photoluminescence is significantly quenched in the presence of diiodomethane, and recovered by removal of the diiodomethane.

A conceptual system on “dynamic-but-tight” peanut-type cage isomers has been constructed via a template of ubiquitous anions. The anions of the cage isomers can be reversibly exchanged without any change in isomeric skeleton.

Systematic interconversion between trigonal prisms [Pd3X6L2] (X− = Cl−, Br−, and I−) and cubic cages [Pd6L8]12+(X−)12 (X− = BF4− and CF3SO3−) via anion exchange was established. Self-assembly of K2PdX4 (X− = Cl− and Br−) with a C3-symmetric tridentate 1,3,5-tris(2-isonicotinamidephenoxy)benzene (L) produces a trigonal prism, [Pd3X6L2]. Further photoreaction of the [Pd3X6L2] (X− = Cl− and Br−) with CH2I2 gives rise to a halide-exchanged species, [Pd3I6L2]. In contrast, anion exchange of [Pd3X6L2] (X− = Cl−, Br−, and I−) with BF4− yields cubic-shaped cages, [Pd6L8]12+(BF4−)12, with an inner cavity of 15.9 × 15.9 × 15.9 A3. Successive anion exchange of [Pd6L8]12+(BF4−)12 with CF3SO3− gives rises to anion-exchanged [Pd6L8]12+(CF3SO3−)12 and vice versa without cage destruction. Thus, the cage system is specifically sensitive to anions, enabling cage formation to recognize the binding affinity and size of various anions.

Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) are essential biothiols for cellular growth, metabolism, and maintenance of a biological system. Thus, the detection of biothiols is highly important for early diagnosis and evaluation of disease progression. In this article, a series of sulfonyl aza-BODIPYs was synthesized, characterized, and examined by 1H-NMR, 13C-NMR, crystallization, photophysical properties and DFT calculation. Among these structures, a fluorescent probe, BDP-1, exhibited selective detection of Cys among various biothiols via nucleophilic aromatic substitution and typical size of Cys molecules. BDP-1 showed color change and near-infrared (NIR) fluorescence enhancement after reaction with Cys to generate BDP-OH, confirmed by HRMS. The red shift of absorption wavelength showed a similar tendency resulting in time-dependent density functional theory (TD-DFT). Furthermore, the calculated detection limit of BDP-1 toward Cys was 5.23 μM. This probe facilitates the colorimetric and fluorescent detection of Cys over other biothiols.

We prepared the monomer PCDA-HP composed of 5-hydroxy-N 1,N 3-bis(pyridin-2-ylmethyl)isophthalamide (HP) as a cadmium ion tweezer and then polymerized them to form a polydiacetylene (PDA)-based sensor (PDA-HP), which displayed selective and sensitive colorimetric and fluorometric change upon addition of a cadmium ion (Cd2+) at both pH 7.4 and 6.8. The PDA-HP polymer was highly selective for Cd2+ over other metal ions with colorimetric change. In addition, the PDA-HP chemosensor also showed a red fluorescence change in the presence of Cd2+ at both pH 7.4 and 6.8. Naked-eye detection of Cd2+ was accomplished in an aqueous solution through a PDA-based sensor system. Finally, the lowest energy structure of an HP chelator was obtained by the crystal structure and density functional theory (DFT) calculations.

Self-assembly of AgPF

Self-assembly of NiX2 (X− = Br− and Cl−) with bidentate dialkyl(3-pyridyl)silane ligands (dialkyl- = (3,3,3-trifluoropropyl)methyl- (L1), = cyclohexylmethyl- (L2), = ethylmethyl- (L3)) gives rise to stable crystals consisting of the Ni3L6 cage motif. Each cage exists as a discrete species encapsulating two halide anions, but its packing mode determines its guest-accessible void volume. The void volume acts as a sustainable reservoir for reversible adsorption/desorption of water in the capacity order Br2@[Ni3L26(H2O)6]Br4·38H2O > Br2@[Ni3L16(H2O)6]Br4·34H2O > Br2@[Ni3L36(H2O)6]Br4·13H2O > Cl2@[Ni3L36Cl3(H2O)3]Cl·5C4H8O.

Cocrystallization of melamine with organic sulfonic acids (1,5-naphthalenedisulfonic acid and 4,4′-biphenyldisulfonic acid) gives rise to 2D porous organic frameworks. Each 2D framework has a diffe...

Self-assembly of AgPF6 with a new C3-symmetric tridentate N-donor ligand gives rise to unusual pseudo-2D porous networks with open channels via the interpenetration of 1D zigzag ladders. The open-c...

The self-assembly of PdX2 (X– = ClO4– and PF6–) with C3-symmetric l- and d-L [L = (2S,2′S,2″S)- and (2R,2′R,2″R)-[benzenetricarbonyltris(azanediyl)]tris(3-phenylpropane-2,1-diyl)triisonicotinate] p...

The construction of a coordination cage in a system of dual anions including hexafluorosilicate was investigated. The self-assembly of Cu(BF4)2 with L in the presence of (NH4)2SiF6 gives rise to a cage of [(SiF6)@Cu2L4](BF4)2, whereas the reaction of CuX2 (X− = NO3− and ClO4−) with L in the presence of (NH4)2SiF6 yields a cage of [(SiF6)@Cu2L4](SiF6). The anion exchange of [(SiF6)@Cu2L4](BF4)2 with NaPF6 in acetone gives rise to a 2D structure of [Cu(PF6)2L2]·C3H6O. Significant catalytic effects on catechol oxidation catalysis in dichloromethane were observed in the order [(SiF6)@Cu2L4](BF4)2·MeOH > [(SiF6)@Cu2L4](SiF6)·6MeOH ≫ [Cu(PF6)2L2]·C3H6O > Cu(BF4)2. The oxidation catalysis reactions using the coordination cages were efficiently completed within 20 min at 40 °C, the performance of which ranks among the most efficient yet recorded.

Significant structural contraction and expansion of flexible Pd6L8 cages by encapsulation of alkyl sulfate were demonstrated. The contact angles on the fine-ground microcrystal layers shift according to the chain length of the alkyl sulfate.

Reaction of Pd(BF4)2 with L (L = bis(pyridin-3-yl-propyl)pyridine-3,5-dicarboxylate) in the 1 : 2 mole ratio gives rise to a spiro-type [PdL2]·(BF4)2·2C6H6·2CH3CN, and further self-assembly of [PdL2]·(BF4)2·2C6H6·2CH3CN with Pd(NO3)2 in the 2 : 1 mole ratio in Me2SO at 90 °C produces a uniquely pliable double cage of [(NO3)2(H2O)2@Pd3L4](BF4)4·6C3H7NO. Both the encapsulated NO3− and the outside BF4− anions are exchanged by X− to form [(X)2@Pd3L4](X′)4 (X− = PF6−, ClO4−, and/or NO3−; X’− = BF4−, PF6−, ClO4−, and NO3−) with all-inclusive pure or mixed anions. The pliable and characteristic properties of the double cages were confirmed by anion exchange of the nestled or outside anions in the present study. This system can be used as a ruler for recognition of ubiquitous polyatomic anions.

The self-assembly of Pd(NO3)2 with L (L = 1,2-bis(dimethyl(pyridin-3-yl)silyl)ethane) gives rise to [PdL2](NO3)2 in high yields. Anion exchange of [PdL2](NO3)2 with X− (X− = BF4−, ClO4−, and PF6−) changes the skeleton into a cage of [(X)@Pd2L4](X)3. Successive anion exchange of [(X)@Pd2L4](X)3 (X− = BF4−, ClO4−, and PF6−) with X− (X− = ReO4− and SiF62−) produces [(ReO4)@Pd2L4](ReO4)3 and [(SiF6)@Pd2L4](SiF6), respectively, irrespective of anion charge. The flexible nature and conformation of cages are significantly dependent on the nestled polyatomic anions. Thus, this system can be used as a molecular recognizer of the size and charge of ubiquitous polyatomic anions.

Self-assembly of ZnX2 (X− = ClO4− and CF3SO3−) with naphthalene-2,6-diyl-diisonicotinate (L) gives rise to the 2D sheet structures with composition of [ZnL2(H2O)2](ClO4)2·H2O and [ZnL2(CF3SO3)2], respectively. [ZnL2(H2O)2](ClO4)2·H2O is packed in an interpenetration mode, whereas [ZnL2(CF3SO3)2] exists as a simple 2D network in the crystalline solid state. These two crystals have been employed as hetero-catalysts for transesterification reactions of phenylacetate with alcohol. The catalytic effect on the transesterification reaction shows the order of [ZnL2(H2O)2](ClO4)2·H2O > Zn(CF3SO3)2 > [ZnL2(OTf)2] > Zn(ClO4)2, which indicate that molecular packing is an important factor in the catalysis.

Self-assembly of CuX2 with C3-symmetric tridentate ligand, 1,3,5-tris(nicotinoyloxy-methyl)benzene (L), affords thermodynamically stable C2-symmetric metallacyclodimers, [Cu2X2L2(H2O)2]X2(H2O)2 (X− = NO3−, BF4−, and ClO4−) in high yields. These cyclodimeric species show the significant anion effects on the catechol oxidation catalysis in chloroform in the order [Cu2(NO3)2L2(H2O)2](NO3)2(H2O)2 > [Cu2(BF4)2L2(H2O)2](BF4)2(H2O)2 > [Cu2(ClO4)2L2(H2O)2](ClO4)2(H2O)2.

Self-assembly of Cu(OTf)2 with a new N,N′,N″-((benzene-1,3,5-triyltris(oxy))tris(benzene-2,1-diyl))trinicotinamide ligand (L) in a mixed solution gives rise to single crystal of [Cu2L2(OTf)3(Sol)(H2O)2]OTf (Sol = Me2CO, H2O, MeOH) cages. Their skeletal structure is a bimetallic cage with copper (II) (Cu(II)) sites of corresponding coordinated solvate molecules. These crystals have been employed as hetero-catalysts for 3,5-di-tert-butylcatechol oxidation, showing significant and different catalytic effects in dichloromethane according to the coordinated solvate molecules in the order Sol = Me2CO > MeOH > H2O. Such notable catalytic effects can be explained by the dissociation ability of coordinated solvate molecules at the catalytic center.

Unusual in situ two-step crystallization on self-assembly of AgX (X– = CF3SO3– and PF6–) with 1,3,5-tris(nicotinoyloxy-methyl)benzene (L) has been carried out. The self-assembly reaction produces initial single crystals consisting of cyclophane-type 30-membered macrocyclic linked one-dimensional (1D) coordination polymers, and then the single crystals are transformed into different morphological crystals consisting of 16-membered macrocyclic linked 1D coordination polymers in the mother liquor. The crystal structures show significant difference in metallophilicity between CF3SO3– and PF6– anion.

Self-assembly of Ag(I) cations with N,N′,N′′-tris(2-(pyridin-4-yl)ethyl)-1,3,5-benzenetricarboxamide (L) produces new 2D metal–organic networks with 108-membered rings, [Ag3L2]. The 2D networks are interlayer-packed, which results in the formation of hydrophobic suprachannels (19.2 × 27.6 A). Around each silver(I) ion, triflate counteranions are confined (2.93(1)–3.041(9) A), thus the hydrophobic suprachannels effectively adsorb a wide range of anthracene substitutes in either a monomeric or an excimeric mode, which makes them potentially useful as energy-transfer materials.

Self-assembly of ZnI2 with di(isoquinolin-5-yl)isophthalate (L) as a new bidentate N-donor gives rise to discrete crown-shaped M2L2 cyclodimers, 3.5CH3CN·0.7THF@[Zn2I4L2]. These metallacyclodimers are composed of a characteristically eclipsed molecular array, resulting in the formation of unusual 10.0 × 15.1 A2 diameter suprachannels. The suprachannels adsorb/desorb various liquid molecules in a rigid manner, which enables scientists to solve the structures of various liquids. This columnar molecular ensemble is an efficient, tolerant, and reproducible suprachannel matrix for structural determination of general liquid compounds via easy single-crystal-to-single-crystal (SCSC) guest exchange without any desolvation process.

A very simple, robust, and pico/nanomolar-sensitive 9,10-diethanolamine-substituted fluorescent Fe3+/CN– probe (PD) was synthesised, and its sensing abilities towards various ions were studied in mixed aqueous media. PD selectively recognised Fe3+ ions through a ‘turn on’ response with an excellent binding constant (Ka, 9.29 × 106 M−1) in 1:2 binding stoichiometry at pH 7.0 in phosphate-buffered saline (PBS). The in situ generated Fe3+·PD ensemble sequentially recognised CN– ions with an excellent binding constant (Ka 1.72 × 108 M−1) via a ‘turn off’ mode by extruding Fe3+ ions from the ensemble. The highly selective sequential ‘on-off’ responses towards Fe3+ and CN– ions were attributed to inhibition and restoration of photoinduced electron transfer (PET) and chelation-induced enhanced fluorescence (CHEF) effects from the chelating N and O heteroatoms. PD was able to detect Fe3+ and CN– ions in real water samples satisfactorily at picomolar to sub-nanomolar levels. A colorimetric assay based on pyrocatechol violet (PCV) was also able to detect Fe3+/CN– in a sequential manner (up to sub-micromolar level) by a change in colour from colourless to yellow/pale green without any interferences from other ions. Based on the complexation and decomplexation mechanism, bio-imaging photonic INHIBIT logic circuit strips were prepared for use under physiological conditions. In addition, solid-phase recognition of Fe3+/CN– ions was demonstrated using cost-effective paper-based strips.

A cyclic manipulation of peanut cage isomers has been achieved via anion exchange and unusual cage isomerism.

The growing accumulation of emerging contaminants in the environment can cause direct and indirect water pollution that puts human lives at risk. The fact that these contaminants are not or cannot be eliminated from the municipal water utilities, poses a significant concern. Researchers are currently pulling massive attention to improve existing technologies, develop new strategies and provide environmentally and durable solutions to mitigate water contamination problems. Adsorption and photodegradation are two of the most sustainable technologies that are used in water purification. These technologies have many advantages because of the economic, simple and easily operated designs needed to treat wastewater. Within these applications, metal organic frameworks (MOFs) are playing a significant role as novel class of porous materials characterized by a crystalline structure. MOFs are considered good candidates to be employed in wastewater treatment technologies because of the tunability of their features. The scope of this review article is to provide a comprehensive description of the recent studies published in the literature about the adsorptive and photocatalytic use of MOFs for the removal of organic emerging contaminants from wastewater. Furthermore, this study briefly highlights the synthesis technologies of MOFs. Finally, future perspective, and challenges associated with MOFs large scale production are discussed.

The self-assembly of PdX