Porous Supramolecular Frameworks Research Articles

A π−π stacked porous framework for highly efficient second near-infrared photothermal effects and photo-thermo-electric conversion

Near-infrared (NIR) photothermal compounds, which convert low-energy NIR photons into heat, have recently attracted significant attention due to their potential applications in many areas such as photothermal imaging, diagnosis and therapy, photosensors, and catalysis. Photothermal conversion efficiency (PCE), a critical parameter of NIR photothermal materials, significantly influences their practical performance. However, exploring highly efficient NIR photothermal compounds, particularly in the NIR-II domain, remains a significant challenge. Herein, we report on a highly efficient NIR-II photothermal compound based on a novel π−π stacked porous framework {[Ni4Cl2(ONDI)2(bpy)4]⋅2Cl⋅2H2O⋅xDMF⋅yH2O}n (1). This compound features a porous supramolecular framework constructed through intermolecular π−π interactions. Additionally, compound 1 exhibits broad optical absorption spanning from the ultraviolet to the NIR region, with an edge extending to 1600 nm. Under irradiation with a 1064 nm laser, compound 1 demonstrates significant NIR-II photothermal effects, achieving a remarkable PCE of 84.4 %, attributed to the formation of charge states and the abundant π−π interactions in its crystal structure. When integrated with commercial thermoelectric generators, compound 1 shows promising potential for photo-thermo-electric conversion, with a maximum open-circuit voltage of 250 mV and 350 mV under irradiation of 1 sun and 2 suns, respectively. Furthermore, the output power density of 1@TEC1-12701 reaches 0.53 W/m2 under 1 sun and 1.23 W/m2 under 2 suns.

Improving Stability, Crystallinity, and Photo‐Responsiveness of Supramolecular Frameworks by Surface Polymerization

AbstractMetal–organic cage‐based photo‐responsive supramolecular frameworks (PSMFs) with permanent porosity have gained attention for their modular properties, controllable functionality, and light‐induced reversible responsiveness. However, their high porosity and photo‐responsive efficiency are often compromised due to poor structural stability upon solvent removal, limiting their potential applications. Here, a solution to overcome this challenge by employing a surface polymerization strategy using isophorone diisocyanate (IDI) to stabilize PSMF (PCC‐20t) is presented. This approach results in the composite of PCC‐20t@PolyIDI, which preserves crystallinity and permanent high‐porosity while avoiding structural collapse commonly observed in highly porous supramolecular frameworks. Moreover, compared to activated PCC‐20t, PCC‐20t@PolyIDI exhibits an 18.6‐fold increase in specific surface area. Remarkably, the structural variability of PCC‐20t@PolyIDI can be observed in the photo‐regulation behavior of CO2 capacity under the irradiation of vis‐ and UV‐light, showing a 27.9% change in adsorption amount for CO2 which is significantly higher than that of the activated PCC‐20t with 7.0% for CO2. Grand Canonical Monte Carlo simulations demonstrate the light‐regulated adsorption performance is attributed to the configuration transformation of azobenzene from trans‐ to buckling state. The findings may pave the way for stabilizing high‐porosity materials to simultaneously meet demands for high‐porosity and photo‐responsive efficiency.

Dynamic and transformable Cu12 cluster-based C-H···π-stacked porous supramolecular frameworks

The assembly of cluster-based π-stacked porous supramolecular frameworks presents daunting challenges, including the design of suitable cluster building units, control of the sufficient C-H···π interactions, trade-off between structural dynamics and stability as well as understanding the resulting collective properties. Herein, we report a cluster-based C-H···π interaction-stacked porous supramolecular framework, namely, Cu12a-π, consisting of Cu12 nanocluster as a 6-connected node, which is further propagated to a dynamic porous supramolecular frameworks via dense intralayer C-H···π interactions, yielding permanent porosity. In addition, Cu12a-π can be transformed into cluster-based nonporous adaptive crystals (Cu12b-NACs) via ligand-exchange following a dissociation-reassembly mechanism. Moreover, Cu12a-π can efficiently remove 97.2% of iodine from saturated iodine aqueous solutions with a high uptake capacity of 2.96 g·g−1. These prospective results positioned at cluster-based porous supramolecular framework and enlighten follow-up researchers to design and synthesize such materials with better performance.

Ni dispersed ultrathin carbon nanosheets as bi-functional oxygen electrocatalyst induced from graphite-like porous supramolecule

Excellent porosity and accessibility are key requirements during carbon-based materials design for energy conversion applications. Herein, a Ni-based porous supramolecular framework with graphite-like morphology (Ni-SOF) was rationally designed as a carbon precursor. Ultrathin carbon nanosheets dispersed with Ni nanoparticles and Ni-Nx sites (Ni@NiNx-N-C) were obtained via in-situ exfoliation during pyrolysis. Due to the hetero-porous structure succeeding from Ni-SOF, the Ni@NiNx-N-C catalyst showed outstanding bifunctional oxygen electrocatalytic activity with a narrow gap of 0.69 V between potential to deliver 10 mA cm−2 oxygen evolution and half-wave potential of oxygen reduction reaction, which even surpassed the Pt/C + IrO2 pair. Therefore, the corresponding zinc-air battery exhibited excellent power output and stability. The multiple Ni-based active sites, the unique 2D structure with a high graphitization degree and large specific surface area synergistically contributed to the excellent bifunctional electrocatalytic activity of Ni@NiNx-N-C. This work provided a novel viewpoint for the development of carbon-based electrocatalyst.

Porous Supramolecular Assembly of Pentiptycene-Containing Gold(I) Complexes: Persistent Excited-State Aurophilicity and Inclusion-Induced Emission Enhancement.

We report herein a porous supramolecular framework formed by a linear mononuclear Au(I) complex (1) via the tongue-and-groove-like joinery between the pentiptycene U-cavities (grooves) and the rod-shaped π-conjugated backbone and alkyl chains (tongues) with the assistance of C-H···π and aurophilic interactions. The framework contains distorted tetrahedral Au4 units, which undergo stepwise and persistent photoinduced Au(I)-Au(I) bond shortening (excited-state aurophilicity), leading to multicolored luminescence photochromism. The one-dimensional pore channels could accommodate different solvates and guests, and the guest inclusion-induced luminescence enhancement (up to 300%) and/or vapochromism are characterized. A correlation between the aurophilic bonding and the luminescence activity is uncovered by TDDFT calculations. Isostructural derivatives 2 and 3 corroborate both the robustness of the porous supramolecular assembly and the mechanisms of the stimulation-induced luminescence properties of 1. This work demonstrates the cooperation of aurophilicity and structural porosity and adaptability in achieving novel supramolecular photochemical properties.

A POM-based porous supramolecular framework for efficient sulfide–sulfoxide transformations with a low molar O/S ratio

A porous supramolecular framework heterogeneously catalyzed the oxidative synthesis of sulfoxides and the detoxification of mustard gas simulants with a low molar O/S ratio.

Porous Pyrene Organic Cage with Unusual Absorption Bathochromic-Shift Enables Visible Light Photocatalysis

Porous Pyrene Organic Cage with Unusual Absorption Bathochromic-Shift Enables Visible Light Photocatalysis

Highly efficient fluorescent chemosensor for nitro antibiotic detection based on luminescent coordination polymers with 2,6-di(4-carboxyphenyl)pyrazine

A series of isostructural porous supramolecular frameworks, {[M(DCPP)(H2O)]·(DMF)}n, are synthesized. The as-obtained fluorescent Zn-MOF has good recognition ability towards nitro-antibiotics with low detection limits and a wide linear range.

Stabilizing the Extrinsic Porosity in Metal–Organic Cages-Based Supramolecular Framework by In Situ Catalytic Polymerization

Porous supramolecular frameworks based on metal–organic cages (MOCs) usually have poor structural stability after activation. This issue narrows the scope of their potential applications, particula...

Synthesis, Adsorption, and Recognition Properties of a Solid Symmetric Tetramethylcucurbit[6]uril-Based Porous Supramolecular Framework

In this work, we reported a porous supramolecular framework (A) constructed of a symmetric tetramethylcucurbit[6]uril (TMeQ[6]) in aqueous HCl solutions; the driving force was the outer surface interaction of cucurbit[n]urils, as well as hydrogen bonding between latticed water molecules and portal carbonyl oxygens of TMeQ[6]. Adsorption experimental results revealed that the porous supramolecular framework can absorb certain fluorophore guests (FGs) to form luminescent assemblies (FG@As) by fluorescence enhancement or colour change, and some of them can respond to certain volatile organic compounds. Thus, the TMeQ[6]-based supramolecular framework could be used as a sensor for certain gas or volatile compounds.

Cucurbit[n]uril-calix[n]arene-based supramolecular frameworks assembled using the outer surface interactions of cucurbit[n]urils

Based on the crystal structures of two cucurbit[6]uril/calix[n]arene-based supramolecular frameworks reported by Long and co-workers, we further investigated the interactions of cucurbit[6]uril with 4-sulfocalix[4]arene and 4-sulfocalix[6]arene using 1H NMR spectroscopy and isothermal titration calorimetry (ITC), respectively. Moreover, solid fluorescent materials were prepared via the adsorption of fluorescent dyes by these porous supramolecular frameworks, which exhibit a selective response to certain volatile organic compounds.

π-π stacking interactions: Non-negligible forces for stabilizing porous supramolecular frameworks.

Revealing the contribution of π-π stacking interactions in supramolecular assembly is important for understanding the intrinsic nature of molecular assembly fundamentally. However, because they are much weaker than covalent bonds, π-π stacking interactions are usually ignored in the construction of porous materials. Obtaining stable porous materials that are only dependent on π-π stacking interactions, despite being very challenging, could address this concern. Here, we present a porous supramolecular framework (π-1) stabilized only by intermolecular π-π stacking interactions. π-1 shows good thermal and chemical stability not only in various organic solvents but also in aqueous solution in a broad pH range. Furthermore, featuring one-dimensional channels with dangling thiolate groups, π-1 exhibits excellent Hg2+ removal performance, with adsorption capacity as high as 786.67 mg g-1 and an adsorption ratio as high as 99.998%. In addition, π-1 also shows high adsorption selectivity to Hg2+ in the presence of a series of interfering ions.

Synthesis, crystallographic and spectral studies of homochiral cobalt(II) and nickel(II) complexes of a new terpyridylaminoacid ligand

Based on a chiral terpyridylaminoacid ligand, a series of homochiral Co(II) and Ni(II) complexes, namely, [Co(H2L)(HL)]·Cl·(PF6)2·2H2O (1), [Ni(H2L)(HL)]·Cl·(PF6)2 (2), [Co2(L)2(CH3OH)(H2O)]·(PF6)2·CH3OH (3), [Ni2(L)2(CH3OH)2]·(PF6)2·2CH3OH (4), [Co2(L)2(N3)2]·3H2O (5), and [Ni2(L)2(SCN)2]·4H2O (6) have been successfully synthesized and characterized by elemental analysis, TGA, spectroscopic methods (IR, CD and electronic absorption spectra) and single-crystal X-ray diffraction structural analysis (HL = (S)-2-((4-([2,2':6′,2″-terpyridin]-4′-yl)benzyl)amino)-4-methylpentanoic acid). In the acidic reaction conditions, one protonated (H2L)+ and one zwitterionic HL only used their terpyridyl groups to chelate one metal ion Co(II) or Ni(II), forming chiral mononuclear cationic complexes 1 or 2. But in the basic and hydro(solvo)thermal reaction conditions, deprotonated ligands (L)‒ acting as bridges used their terpyridyl and amino acid groups to link with two Co(II) or Ni(II) ions, fabricating chiral dinuclear metallocyclic complexes 3–6. Those chiral mononuclear and dinuclear complexes whose chirality originates in the homochiral ligand HL further self-assemble into higher-dimensional homochiral supramolecular frameworks through intermolecular hydrogen-bonding and π···π interactions. Notably, the coordination mode, hydrogen-bonding site, and existence form of HL ligand can be controlled by the protonation of its amino group, and the architectural diversity of those supramolecular frameworks is adjusted by pH and counter anions. Very interestingly, the 3D porous supramolecular frameworks built up from the huge chiral mononuclear cationic complexes 1 and 2 have novel helical layers only formed through every right-handed helical chain intertwining with two adjacent same helical chains, and the 2D supramolecular helicate 5 consists of two types of left-handed helical chains.

Multiple Efficient Fluorescence Emission from Cucurbit[10]uril-[Cd4Cl16]8--Based Pillared Diamond Porous Supramolecular Frameworks.

Cucurbit[10]uril (Q[10] or CB[10]), with the largest rigid cavity (ca. 1.0 nm) yet characterized in the cucurbiturils family, and indeed among all artificial macrocyclic receptors to date, has been successfully exploited to construct a novel Q[10]-[Cd4Cl16]8--based pillared diamond porous supramolecular framework. Single-crystal X-ray diffraction analysis revealed that the three-dimensional open-nanotube-type porous framework is constructed from free Q[10] molecules and [Cd4Cl16]8- cluster anions through the outer surface interactions of Q[10]. Notably, the Q[10]-based porous framework host can accommodate guest dyes, such as rhodamine B (G1), pyrenemethanamine hydrochloride (G2), and bathocuproine hydrochloride (G3), to form solid materials with efficient red-green-blue (RGB) fluorescence. This work not only exemplifies a facile approach for the construction of macrocycle-based porous frameworks but also offers a simple, lower cost, yet still highly efficient means of preparing multi-emitting, including white-light-emitting, solid luminescent materials.

Construction of metal–organic frameworks from 3-(6-oxo-6,9-dihydro-1H-purin-1-yl)propionate

A series of metal–organic frameworks built from a propionate-functionalized purine-containing ligand 3-(6-oxo-6,9-dihydro-1H-purin-1-yl)propanoic acid (H2L), {[La(HL)3(H2O)2]·2H2O}n (1), {[Ce(HL)3(H2O)2]·4H2O}n (2), [Co(HL)2(H2O)2]n (3), {[Cd(L)(H2O)]·0.5H2O}n (4) and {[Pb(HL)(C2O4)0.5(H2O)]·2H2O}n (5), was synthesized and characterized. Isostructural 1 and 2 have polymeric chain structures further linked into 3-D porous supramolecular frameworks with 1-D open channels through complicated interchain hydrogen bonding interactions. At 77 K and 1 bar, the dehydrated porous materials 1 and 2 show adsorption behaviors with maximum nitrogen uptakes of 14 and 23 mL g−1, respectively. Complexes 3–5 are 2-D coordination polymers but have different topological structures. Metallohelicate 3 has (4,4) nets composed of left- and right-handed metal–organic helices sharing the common metal centers, but metallohelicate 4 possesses (4·82) topology and 5 has 63-topological structure. In 3 and 5, the polymeric layers are further assembled through regular interlayer hydrogen bonding interactions to form 3-D supramolecular frameworks. Additionally, the thermostabilities of 1–5 as well as the magnetism of 3 were also investigated.

Syntheses, structures, and properties of nine d10or p-block coordination polymers based on a ligand containing both terpyridyl and sulfo groups

Nine new coordination compounds, namely, {[Zn(HDSPTP)2(H2O)4]·6H2O}n (H2DSPTP = 4′-(2,4-disulfophenyl)-4,2′:6′,4′′-terpyridine, (1), [Cd(DSPTP)(H2O)2]n (2), {[Ag(HDSPTP)]·30H2O}n (3), {[Ag(HDSPTP)(H2O)]·3H2O}n (4), [Ag2(DSPTP)]n (5), {[Ag4(DSPTP)2(H2O)3]·2H2O}n (6), [Pb(DSPTP)(H2O)2]n (7), {[Pb(DSPTP)(H2O)3]·3H2O}n (8), and [PbK(DSPTP)(NO3)(H2O)2]·H2O}n (9), were synthesized by introducing a ligand with both terpyridyl and sulfo groups as organic linkers. The reaction of H2DSPTP with Zn(II) salts only resulted in a mononuclear complex (compound 1), in which most donor groups appear uncoordinated, whereas the reaction with Cd(II) salts under similar conditions resulted in a three-dimensional (3D) twofold interpenetrated dia framework (compound 2). The reactions of H2DSPTP with AgCF3CO2 or AgNO3 resulted in compounds 3–6 with different structures: a porous supramolecular framework via interlaced packing of one-dimensional (1D) coordination chains (compound 3), a two-dimensional (6,3) network based on coordination bonds and Ag⋯O interactions (compound 4), a 3D framework based on 1D [Ag2(2-SO3−)2]n secondary building blocks (compound 5), and a twofold interpenetrated framework with a binodal (4,6)-connected fsh topology based on planar tetranuclear SBUs as nodes (compound 6). The reactions of H2DSPTP with Pb(NO3)2 resulted in the following three compounds: a 3D twofold interpenetrated dia framework (complex 7), a twofold interpenetrated (6,3) network (compound 8), and a 3D complicated framework based on tetranuclear SBUs, double-bridge DSPTP2− ligands, and [K(H2O)]+ species (compound 9). The structural diversity is mainly attributed to the rich coordination behaviors of the HDSPTP−/DSPTP2− ligands and the metal center and can be controllably synthesized by altering the metal to ligand ratio, added alkali, and the pH value for the Ag(I) and Pb(II) compounds. Compound 2 exhibits a high thermal stability above 500 °C, undergoes a crystalline–amorphous–crystalline phase transition as temperature is increased from 25 °C to 500 °C, and shows an amorphous–crystalline phase transition when rehydrated. Moreover, the luminescence properties of all the compounds were also investigated.

Rational design of a pyrene based luminescent porous supramolecular framework: excimer emission and energy transfer

Based on rational design and synthesis approach, a pyrene based supramolecular flexible porous framework of Zn(ii) has been synthesized. It shows excimer emission and has been exploited for light harvesting application.

Breaking the Mirror: pH‐Controlled Chirality Generation from a meso Ligand to a Racemic Ligand

To study the conversion from a meso form to a racemic form of tetrahydrofurantetracarboxylic acid (H(4)L), seven novel coordination polymers were synthesized by the hydrothermal reaction of Zn(NO(3))(2)6 H(2)O with (2S,3S,4R,5R)-H(4)L in the presence of 1,10-phenanthroline (phen), 2,2'-bipyridine (2,2'-bpy), or 4,4'-bipyridine (4,4'-bpy): [Zn(2){(2S,3S,4R,5R)-L}(phen)(2)(H(2)O)]2 H(2)O (1), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L}(phen)(2)(H(2)O)(2)] (2), [Zn(2){(2S,3S,4R,5R)-L}(H(2)O)(2)]H(2)O (3), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L} (2,2'-bpy)(2)(H(2)O)(2)]2 H(2)O (4), [Zn(2) {(2S,3S,4R,5R)-L}(2,2'-bpy)(H(2)O)] (5), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L} (4,4'-bpy)(2)(H(2)O)(2)] (6), and [Zn(2) {(2S,3S,4R,5R)-L}(4,4'-bpy)(H(2)O)] 2 H(2)O (7). These complexes were obtained by control of the pH values of reaction mixtures, with an initial of pH 2.0 for 1, 2.5 for 2, 4, and 6, and 4.5 for 3, 5, and 7, respectively. The expected configuration conversion has been successfully realized during the formation of 2, 4, and 6, and the enantiomers of L, (2S,3R,4R,5R)-L and (2S,3S,4S,5R)-L, are trapped in them, whereas L ligands in the other four complexes retain the original meso form, which indicates that such a conversion is possibly pH controlled. Acid-catalyzed enol-keto tautomerism has been introduced to explain the mechanism of this conversion. Complex 1 features a simple 1D metal-L chain that is extended into a 3D supramolecular structure by pi-pi packing interactions between phen ligands and hydrogen bonds. Complex 2 has 2D racemic layers that consist of centrosymmetric bimetallic units, and a final 3D supramolecular framework is formed by the interlinking of these layers through pi-pi packing interactions of phen. Complex 3 is a 3D metal-organic framework (MOF) involving meso-L ligands, which can be regarded as (4,6)-connected nets with vertex symbol (4(5).6)(4(7).6(8)). Complexes 4 and 5 contain 2D racemic layers and (6,3)-honeycomb layers, respectively, both of which are combined into 3D supramolecular structures through pi-pi packing interactions of 2,2'-bpy. The structure of complex 6 is a 2D network formed by 4,4'-bpy bridging 1D tubes, which consist of metal atoms and enantiomers of L. These layers are connected through hydrogen bonds to give the final 3D porous supramolecular framework of 6. Complex 7 is a 3D MOF with novel (3,4,5)-connected (6(3))(4(2).6(4))(4(2).6(6).8(2)) topology. The thermal stability of these compounds was also investigated.

Thermally stable porous supramolecular frameworks based on the metal and π–π stacking directed self‐assembly of 2,6‐pyridyldicarboxylic acid bis‐4‐pyridylamide

AbstractWe report the formation of two thermally stable supramolecular structures based on 2,6‐pyridyldicarboxylic acid bis‐4‐pyridylamide (PyI) and bis(hexafluoroacetylacetonato)manganese(II) that exhibits a microporous structure with cavities bearing hydrogen bonding motifs that can enclathrate acetone and methanol molecules via well‐positioned hydrogen bonding interactions. Single‐crystal x‐ray diffraction in combination with thermogravimetric analysis and X‐ray powder diffraction (XRPD) studies were utilized to study the structure and thermal behavior of trans‐[Mn(hfacac)2(PyI)2]·2(CH3)2CO (1) and trans‐[Mn(hfacac)2(PyI)2]·2CH3OH (2). Our studies indicated that 1 and 2 are isostructural with respect to their supramolecular assembly and trap solvent molecules along the crystallographic b direction via the inwardly directed hydrogen bonding motifs of the PyI component. These solvent molecules can be thermally removed to generate a crystalline material with micropores bearing hydrogen bonding rich sites within an overall supramolecular matrix similar to 1 and 2. The removal of the guest solvent molecules is reversible and can be followed with XRPD. Copyright © 2003 John Wiley & Sons, Ltd.