Metalation of metal-organic frameworks: fundamentals and applications.

Metalation of metal-organic frameworks (MOFs) has been developed as a prominent strategy for materials functionalization for pore chemistry modulation and property optimization. By introducing exotic metal ions/complexes/nanoparticles onto/into the parent framework, many metallized MOFs have exhibited significantly improved performance in a wide range of applications. In this review, we focus on the research progress in the metalation of metal-organic frameworks during the last five years, spanning the design principles, synthetic strategies, and potential applications. Based on the crystal engineering principles, a minor change in the MOF composition through metalation would lead to leveraged variation of properties. This review starts from the general strategies established for the incorporation of metal species within MOFs, followed by the design principles to graft the desired functionality while maintaining the porosity of frameworks. Facile metalation has contributed a great number of bespoke materials with excellent performance, and we summarize their applications in gas adsorption and separation, heterogeneous catalysis, detection and sensing, and energy storage and conversion. The underlying mechanisms are also investigated by state-of-the-art techniques and analyzed for gaining insight into the structure-property relationships, which would in turn facilitate the further development of design principles. Finally, the current challenges and opportunities in MOF metalation have been discussed, and the promising future directions for customizing the next-generation advanced materials have been outlined as well.

Clinical effects of combined use of carbamazepine and amitriptyline in the treatment of diabetic neuropathy with concurrent diabetic foot.

OBJECTIVE: This study aims to analyze the clinical effects of combining carbamazepine and amitriptyline in the treatment of diabetic neuropathy with concurrent diabetic foot. METHODS: A total of 120 diabetic neuropathy patients treated at our hospital from June 2022 to November 2023 were included in the study. Patients meeting the inclusion criteria were registered, and their basic data were collected. The patients were randomly divided into two groups: the control group treated with amitriptyline and the study group treated with a combination of carbamazepine and amitriptyline. RESULTS: The study group demonstrated significantly better clinical efficacy compared to the control group (p < 0.05). There were no significant differences in psychological status and pain perception before treatment between the two groups (p > 0.05). However, post-treatment, the study group showed improved psychological status, reduced pain perception, and overall better quality of life in both physiological and psychological dimensions compared to the control group (p < 0.05). CONCLUSION: The combined use of carbamazepine and amitriptyline in the treatment of diabetic neuropathy with concurrent diabetic foot yields positive clinical outcomes. It effectively alleviates symptoms, improves psychological well-being, reduces pain sensation, and enhances overall quality of life. These findings can guide physicians in adopting a more evidence-based treatment approach and provide patients with more effective individualized treatment strategies.

Family functioning and patients' depressive symptoms: comparison in perceived family function between patients who had an acute ischaemic stroke and their primary family caregivers - a cross-sectional study.

OBJECTIVES: This study aims to compare perceived family functioning between Chinese patients who had an acute ischaemic stroke (AIS) and family caregivers, and explore the association between family functioning and patients' depressive symptoms. DESIGN: This is a cross-sectional study design. SETTING: Stroke centres of two tertiary hospitals in Nanjing, China. PARTICIPANTS: One hundred and sixty-nine dyads of patients who had an AIS and family caregivers. PRIMARY AND SECONDARY OUTCOME MEASURES: Family functioning of patients who had an AIS and their primary family caregivers was assessed by the Family Assessment Device (FAD, Chinese version). Depressive symptoms of patients who had an AIS was assessed by the Centre for Epidemiological Studies Depression Scale. We test the agreement and differences in family functioning. Multivariate linear regression models were used to test the association of differences of family functioning within dyads with patients' depressive symptoms. RESULTS: AIS families demonstrated unhealthy family functioning. A total of 115 patients (76.9%) and 124 caregivers (73.4%) had a score of 2 or higher in FAD-general functioning (GF), indicating unhealthy family functioning. The intraclass correlation coefficient of FAD subdomain between patients who had an AIS and caregivers ranged from 0.15 to 0.55, which indicating the agreement of family functioning within dyads was poor to moderate. There was a significant difference between the FAD-GF scores of the patients and those of their caregivers (Z=-2.631, p=0.009), with caregivers reporting poorer general family functioning. Poor family functioning and greater difference of perceived family functioning within dyads were related to higher level of patients' depressive symptoms (ß=5.163, p<0.001, ß=5.534, p<0.001, respectively). CONCLUSIONS: These findings indicate that healthcare professionals should assess family functioning in both patients who had a stroke and caregivers. Improvement of family function and decreasing discrepancies within dyads may be helpful for relieving patients' depressive symptoms.

The Effect of Pendent Groups upon Flexibility in Coordination Networks with Square Lattice Topology.

Gas or vapor-induced phase transformations in flexible coordination networks (CNs) offer the potential to exceed the performance of their rigid counterparts for separation and storage applications. However, whereas ligand modification has been used to alter the properties of such stimulus-responsive materials, they remain understudied compared with their rigid counterparts. Here, we report that a family of Zn2+ CNs with square lattice (sql) topology, differing only through the substituents attached to a linker, exhibit variable flexibility. Structural and CO2 sorption studies on the sql networks, [Zn(5-Ria)(bphy)]n, ia = isophthalic acid, bphy = 1,2-bis(pyridin-4-yl)hydrazine, R = -CH3, -OCH3, -C(CH3)3, -N=N-Ph, and -N=N-Ph(CH3)2, 2-6, respectively, revealed that the substituent moieties influenced both structural and gas sorption properties. Whereas 2-3 exhibited rigidity, 4, 5, and 6 exhibited reversible transformation from small pore to large pore phases. Overall, the insight into the profound effect of pendent moieties of linkers upon phase transformations in this family of layered CNs should be transferable to other CN classes.

Dynamic Changes of ORF1ab and N Gene Ct Values in COVID-19 Omicron Inpatients of Different Age Groups - Beijing Municipality, China, November-December 2022.

Introduction: In November 2021, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant was identified as the variant of concern and has since spread globally, replacing other cocirculating variants. To better understand the dynamic changes in viral load over time and the natural history of the virus infection, we analyzed the expression of the open reading frames 1ab (ORF1ab) and nucleocapsid (N) genes in patients infected with Omicron. Methods: We included patients initially admitted to the hospital for SARS-CoV-2 infection between November 5 and December 25, 2022. We collected daily oropharyngeal swabs for quantitative reverse transcriptase-polymerase chain reaction tests using commercial kits. We depicted the cycle threshold (Ct) values for amplification of ORF1ab and N genes from individual patients in age-specific groups in a time series. Results: A total of 480 inpatients were included in the study, with a median age of 59 years (interquartile range, 42 to 78; range, 16 to 106). In the <45-year-old age group, the Ct values for ORF1ab and N gene amplification remained below 35 for 9.0 and 11.5 days, respectively. In the ≥80-year-old age group, the Ct values for ORF1ab and N genes stayed below 35 for 11.5 and 15.0 days, respectively, which was the longest among all age groups. The Ct values for N gene amplification took longer to rise above 35 than those for ORF1ab gene amplification. Conclusion: The time to test negative varied among different age groups, with viral nucleic acid shedding taking longer in older age groups compared to younger age groups. As a result, the time to resolution of Omicron infection increased with increasing age.

Pore Environment Optimization of Microporous Metal-Organic Frameworks with Huddled Pyrazine Pillars for C2H2/CO2 Separation.

Metal-organic frameworks (MOFs) have been proven promising in addressing many critical issues related to gas separation and purification. However, it remains a great challenge to optimize the pore environment of MOFs for purification of specific gas mixtures. Herein, we report the rational construction of three isostructural microporous MOFs with the 4,4',4"-tricarboxyltriphenylamine (H3TCA) ligand, unusual hexaprismane Ni6O6 cluster, and functionalized pyrazine pillars [PYZ-x, x = -H (DZU-10), -NH2 (DZU-11), and -OH (DZU-12)], where the building blocks of Ni6O6 clusters and huddled pyrazine pillars are reported in porous MOFs for the first time. These building blocks have enabled the resulting materials to exhibit good chemical stability and variable pore chemistry, which thus contribute to distinct performances toward C2H2/CO2 separation. Both single-component isotherms and dynamic column breakthrough experiments demonstrate that DZU-11 with the PYZ-NH2 pillar outperforms its hydrogen and hydroxy analogues. Density functional theory calculations reveal that the higher C2H2 affinity of DZU-11 over CO2 is attributed to multiple electrostatic interactions between C2H2 and the framework, including strong C≡C···H-N (2.80 Å) interactions. This work highlights the potential of pore environment optimization to construct smart MOF adsorbents for some challenging gas separations.

Structural Phase Transformations Induced by Guest Molecules in a Nickel-Based 2D Square Lattice Coordination Network.

Herein, we report the crystal structure and guest binding properties of a new two-dimensional (2D) square lattice (sql) topology coordination network, sql-(azpy)(pdia)-Ni, which is comprised of two linker ligands with diazene (azo) moieties, (E)-1,2-di(pyridin-4-yl)diazene(azpy) and (E)-5-(phenyldiazenyl)isophthallate(pdia). sql-(azpy)(pdia)-Ni underwent guest-induced switching between a closed (nonporous) ß phase and several open (porous) α phases, but unlike the clay-like layer expansion to distinct phases previously reported in switching sql networks, a continuum of phases was formed. In effect, sql-(azpy)(pdia)-Ni exhibited elastic-like properties induced by adaptive guest binding. Single-crystal X-ray diffraction (SCXRD) studies of the α phases revealed that the structural transformations were enabled by the pendant phenyldiazenyl moiety on the pdia2- ligand. This moiety functioned as a type of hinge to enable parallel slippage of layers and interlayer expansion for the following guests: N,N-dimethylformamide, water, dichloromethane, para-xylene, and ethylbenzene. The slippage angle (interplanar distances) ranged from 54.133° (4.442 Å) in the ß phase to 69.497° (5.492 Å) in the ethylbenzene-included phase. Insight into the accompanying phase transformations was also gained from variable temperature powder XRD studies. Dynamic water vapor sorption studies revealed a stepped isotherm with little hysteresis that was reversible for at least 100 cycles. The isotherm step occurred at ca. 50% relative humidity (RH), the optimal RH value for humidity control.

The moderating effect of cognitive reserve on cognitive function in patients with Acute Ischemic Stroke.

Background: Recovery of cognitive function after stroke has inter-individual variability. The theory of cognitive reserve offers a potential explanation of the variability in cognitive function after stroke. Objective: This study aimed to investigate the moderating effect of cognitive reserve on the relationship between the stroke severity and cognitive function after stroke. Materials and methods: A total of 220 patients with Acute Ischemic Stroke (AIS) were recruited in 2021 from two stroke centers in Nanjing, China. The National Institutes of Health Stroke Scale (NIHSS) was used to assess stroke severity upon admission. Cognitive Reserve Index questionnaire (CRIq) and validated Montreal Cognitive Assessment, Changsha Version (MoCA-CS) were used to assess cognitive reserve and cognitive function within 7 days after stroke onset, respectively. A series of multivariate linear regression models were applied to test the moderating effect of cognitive reserve. Results: Patients with a higher level of cognitive reserve had better cognitive function after stroke compared with those with a lower level of cognitive reserve (ß = 0.074, p = 0.003). The interaction of NIHSS and cognitive reserve was statistically significant (ß = -0.010, p = 0.045) after adjusting for some key covariates [e.g., age, marital status, Oxfordshire Community Stroke Project (OCSP) classification, Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification, cerebral vascular stenosis, diabetes and atrial fibrillation]. Conclusion: Cognitive reserve may help to buffer the effect of stroke-related pathology on cognitive decline in Chinese acute stroke patients. Enhancing cognitive reserve in stroke patients may be one of the potential strategies for preventing vascular dementia.

A Novel Technique of Urethroplasty Could Reduce Urethra-Related Complications in Phalloplasty With Urethral Lengthening.

INTRODUCTION: Urethral lengthening in phalloplasty could bring many postoperative complications, such as urethra fistula and stricture, which greatly affects the patient's mental health and quality of life. AIM: To describe a novel technique of vaginal mucosal graft for prelamination urethra (VMGPU) combined with modified urethral anastomosis (MUA) for the reconstruction of a neourethra. METHODS: A retrospective study of transgender men between January 2006 and March 2021 was conducted. Patients were divided into three groups according to the surgical methods : traditional group（TG，VMGPU group（VG） and VMGPU+MUA group (VMG). MAIN OUTCOME MEASURE: The main outcomes measures were demographics, surgical characteristics, complications, International Prostate Symptom Score（IPSS，Quality of Life（QOL） score，and voiding frequency conditions. RESULTS: Of 80 eligible transgender men（TG:n = 39，VG:n = 31, VMG:n = 10), the urethral fistula developed in 19/39 (49%) patients in TG, 8/31 (26%) in VG, and 1/10 (10%) in VMG (P = 0.034). The urethral stricture formed in 15/39 (38%) patients in TG, 4/31 (13%) in VG, and 1/10 (10%) in VMG (P = 0.028). Compared with TG, the VG got more favorable IPSS. The QOL scores showed that patients in VG or VMG were more satisfied with their postoperative status. CLINICAL IMPLICATIONS: VMGPU combined with MUA may help reduce urethral complications for transgender men who wish to undergo phalloplasty with urethral lengthening. STRENGTH & LIMITATIONS: VMGPU combined with MUA focuses on reducing the urethra-related complications in the anastomotic stoma between the fixed and the penile urethra, which has not been noticed in the past. The limitations of this study are that the retrospective study design is prone to bias; the study using VMGPU+MUA technique is only in the preliminary stage, and more cases are needed to prove its effectiveness; the median follow-up in VMG was only 2 years, and longer-term follow-up results are inconclusive; the IPSS, QOL, and the voiding frequency chart were not validated in transgender men. CONCLUSION: Our pilot study suggests that VMGPU combined with MUA may reduce the urethra-related complications, especially the urethral fistula in the anastomosis stoma between the fixed and the penile urethra. Gao H, Wu D, Kong X, et al. A Novel Technique of Urethroplasty Could Reduce Urethra-Related Complications in Phalloplasty With Urethral Lengthening. Sex Med 2022;10:100571.

Trace removal of benzene vapour using double-walled metal-dipyrazolate frameworks.

In principle, porous physisorbents are attractive candidates for the removal of volatile organic compounds such as benzene by virtue of their low energy for the capture and release of this pollutant. Unfortunately, many physisorbents exhibit weak sorbate-sorbent interactions, resulting in poor selectivity and low uptake when volatile organic compounds are present at trace concentrations. Herein, we report that a family of double-walled metal-dipyrazolate frameworks, BUT-53 to BUT-58, exhibit benzene uptakes at 298 K of 2.47-3.28 mmol g-1 at <10 Pa. Breakthrough experiments revealed that BUT-55, a supramolecular isomer of the metal-organic framework Co(BDP) (H2BDP = 1,4-di(1H-pyrazol-4-yl)benzene), captures trace levels of benzene, producing an air stream with benzene content below acceptable limits. Furthermore, BUT-55 can be regenerated with mild heating. Insight into the performance of BUT-55 comes from the crystal structure of the benzene-loaded phase (C6H6@BUT-55) and density functional theory calculations, which reveal that C-H···X interactions drive the tight binding of benzene. Our results demonstrate that BUT-55 is a recyclable physisorbent that exhibits high affinity and adsorption capacity towards benzene, making it a candidate for environmental remediation of benzene-contaminated gas mixtures.

Chemically Stable Metal-Organic Frameworks: Rational Construction and Application Expansion.

Metal-organic frameworks (MOFs) have been attracting tremendous attention owing to their great structural diversity and functional tunability. Despite numerous inherent merits and big progress in the fundamental research (synthesizing new compounds, discovering new structures, testing associated properties, etc.), poor chemical stability of most MOFs severely hinders their involvement in practical applications, which is the final goal for developing new materials. Therefore, constructing new stable MOFs or stabilizing extant labile MOFs is quite important. As with them, some "potential" applications would come true and a lot of new applications under harsh conditions can be explored. Efficient strategies are being pursued to solve the stability problem of MOFs and thereby achieve and expand their applications.In this Account, we summarize the research advance in the design and synthesis of chemically stable MOFs, particularly those stable in acidic, basic, and aqueous systems, as well as in the exploration of their applications in several expanding fields of environment, energy, and food safety, which have been dedicated in our lab over the past decade. The strategies for accessing stable MOFs can be classified into: (a) assembling high-valent metals (hard acid, such as Zr4+, Al3+) with carboxylate ligands (hard base) for acid-stable MOFs; (b) combining low-valent metals (soft acid, such as Co2+, Ni2+) and azolate ligands (soft base, such as pyrazolate) for alkali-resistant MOFs; (c) enhancing the connectivity of the building unit; (d) contracting or rigidifying the ligand; (e) increasing the hydrophobicity of the framework; and (f) substituting liable building units with stable ones (such as metal metathesis) to obtain robust MOFs. In addition, other factors, including the geometry and symmetry of building units, framework-framework interaction, and so forth, have also been taken into account in the design and synthesis of stable MOFs. On the basis of these approaches, the stability of resulting MOFs under corresponding conditions has been remarkably enhanced.With high chemical stability achieved, the MOFs have found many new and significant applications, aiming at addressing global challenges related to environmental pollution, energy shortage, and food safety.A series of stable MOFs have been constructed for detecting and eliminating contaminations. Various fluorescent MOFs were rationally customized to be powerful platforms for sensing hazardous targets in food and water, such as dioxins, antibiotics, veterinary drugs, and heavy metal ions. Some hydrophobic MOFs even showed effective and specific capture of low-concentration volatile organic compounds.Novel MOFs with record-breaking acid/base/nucleophilic regent resistance have expanded their application scope under harsh conditions. BUT-8(Cr)A, as the most acid-stable MOF yet, showed reserved structural integrity in concentrated H2SO4 and recorded high proton conductivity; the most alkali-resistant MOF, PCN-601, retained crystallinity even in boiling saturated NaOH aqueous solution, and such base-stable MOFs composed of non-noble metal clusters and poly pyrazolate ligands also demonstrated great potential in heterogeneous catalysis in alkaline/nucleophilic systems for the first time.It is believed that this Account will provide valuable references on stable MOFs' construction as well as application expansion toward harsh conditions, thereby being helpful to promote MOF materials to step from fundamental research to practical applications.

A Practice of Reticular Chemistry: Construction of a Robust Mesoporous Palladium Metal-Organic Framework via Metal Metathesis.

Constructing stable palladium(II)-based metal-organic frameworks (MOFs) would unlock more opportunities for MOF chemistry, particularly toward applications in catalysis. However, their availability is limited by synthetic challenges due to the inertness of the Pd-ligand coordination bond, as well as the strong tendency of the Pd(II) source to be reduced under typical solvothermal conditions. Under the guidance of reticular chemistry, herein, we present the first example of an azolate Pd-MOF, BUT-33(Pd), obtained via a deuterated solvent-assisted metal metathesis. BUT-33(Pd) retains the underlying sodalite network and mesoporosity of the template BUT-33(Ni) and shows excellent chemical stability (resistance to an 8 M NaOH aqueous solution). With rich Pd(II) sites in the atomically precise distribution, it also demonstrates good performances as a heterogeneous Pd(II) catalyst in a wide application scope, including Suzuki/Heck coupling reactions and photocatalytic CO2 reduction to CH4. This work highlights a feasible approach to reticularly construct noble metal based MOFs via metal metathesis, in which various merits, including high chemical stability, large pores, and tunable functions, have been integrated for addressing challenging tasks.

In Situ Porphyrin Substitution in a Zr(IV)-MOF for Stability Enhancement and Photocatalytic CO2 Reduction.

Despite numerous inherent merits of metal-organic frameworks (MOFs), structural fragility has imposed great restrictions on their wider involvement in many applications, such as in catalysis. Herein, a strategy for enhancing stability and enabling functionality in a labile Zr(IV)-MOF has been proposed by in situ porphyrin substitution. A size- and geometry-matched robust linear porphyrin ligand 4,4'-(porphyrin-5,15-diyl)dibenzolate (DCPP2- ) is selected to replace the 4,4'-(1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-2,7(1H,3H,6H,8H)-diyl)dibenzoate (NDIDB2- ) ligand in the synthesis of BUT-109(Zr), affording BUT-110 with varied porphyrin contents. Compared to BUT-109(Zr), the chemical stability of BUT-110 series is greatly improved. Metalloporphyrin incorporation endows BUT-110 MOFs with high catalytic activity in the photoreduction of CO2 , in the absence of photosensitizers. By tuning the metal species and porphyrin contents in BUT-110, the resulting BUT-110-50%-Co is demonstrated to be a good photocatalyst for selective CO2 -to-CO reduction, via balancing the chemical stability, photocatalytic efficiency, and synthetic cost. This work highlights the advantages of in situ ligand substitution for MOF modification, by which uniform distribution and high content of the incoming ligand are accessible in the resulting MOFs. More importantly, it provides a promising approach to convert unstable MOFs, which mainly constitute the vast MOF database but have always been neglected, into robust functional materials.

Person-Centered Communication Between Health Care Professionals and COVID-19-Infected Older Adults in Acute Care Settings: Findings From Wuhan, China.

OBJECTIVES: The current study aims to explore person-centered communication between health care professionals and COVID-19-infected older patients in acute care settings. METHODS: The current qualitative study explored the communication between professionals and COVID-19-infected older adults in the acute care setting through 2 rounds of interviews with physicians and nurses who provided direct care and treatment for COVID-19-infected older patients in Wuhan, China. We explored the possibilities and significance of facilitating effective communication despite multiple challenges in the pandemic. Conventional content analysis was adopted to analyze the rich data collected from our participants. RESULTS: It is possible and necessary to initiate and sustain person-centered communication despite multiple challenges brought by the pandemic. The achievement of person-centered communication can play significant roles in addressing challenges, building mutual trust, improving quality of care and relationships, and promoting treatment adherence and patients' psychological well-being. DISCUSSION: It is challenging for health care professionals to provide care for COVID-19-infected older adults, especially for those with cognitive and sensory impairment, in acute care settings. Facilitating person-centered communication is a significant strategy in responding to the pandemic crisis and a core element of person-centered care.

A Green-Emission Metal-Organic Framework-Based Nanoprobe for Imaging Dual Tumor Biomarkers in Living Cells.

The modular nature of metal-organic frameworks (MOFs) permits their tunable structure and function for target application, such as in biomedicine. Herein, a green-emission Zr(IV)-MOF (BUT-88) was constructed from a customized luminescent carbazolyl ligand. BUT-88 represents the first bcu-type MOF with both organic linker and metal node in eight connections and shows medium-sized pores, rich accessible linking sites, and good water stability and biocompatibility. In virtue of these merits, BUT-88 was then fabricated into a MOF-based fluorescent nanoprobe, drDNA-BUT-88. Using it, the live-cell imaging of dual tumor biomarkers was achieved for the first time upon a MOF-based probe, offering enhanced detection precision in early cancer diagnosis. Particularly, the probe showed efficient ratiometric fluorescent sensing toward the cytoplasmic biomarker microRNA-21, further improving the detection accuracy at the cellular level. In this work, the elaborate combination of MOF engineering and the fluorescent detection technique has contributed a facile biosensing platform, unlocking more possibilities of MOF chemistry.

Kinetically Controlled Reticular Assembly of a Chemically Stable Mesoporous Ni(II)-Pyrazolate Metal-Organic Framework.

The application scope of metal-organic frameworks (MOFs) is severely restricted by their weak chemical stability and limited pore size. A robust MOF with large mesopores is highly desired, yet poses a great synthetic challenge. Herein, two chemically stable Ni(II)-pyrazolate MOFs, BUT-32 and -33, were constructed from a conformation-matched elongated pyrazolate ligand through the isoreticular expansion. The two MOFs share the same sodalite-type net, but have different pore sizes due to the network interpenetration in BUT-32. Controlled syntheses of the two MOFs have been achieved through precisely tuning reaction conditions, where the microporous BUT-32 was demonstrated to be a thermodynamically stable product while the mesoporous BUT-33 is kinetically favored. To date, BUT-32 represents the first example of Ni4-pyrazolate MOF whose structure was unambiguously determined by single-crystal X-ray diffraction. Interestingly, the kinetic product BUT-33 integrates 2.6 nm large mesopores with accessible Ni(II) active sites and remarkable chemical stability even in 4 M NaOH aqueous solution and 1 M Grignard reagent. This MOF thus demonstrated an excellent catalytic performance in carbon-carbon coupling reactions, superior to other Ni(II)-MOFs including BUT-32. These findings highlight the importance of kinetic control in the reticular synthesis of mesoporous MOFs, as well as their superiority in heterogeneous catalysis.

Reaction duration-dependent formation of two Cu(ii)-MOFs with selective adsorption properties of C3H4 over C3H6.

The formation of metal-organic frameworks (MOFs) under given reaction conditions depends on various factors including reaction duration, temperature, used solvent, system pH, and others. Among them, the reaction duration is relatively less investigated. In this work, based on a Cu(ii)-MOF system, the reaction duration was found to play an important role in directing the formation of two different products, (NH2(CH3)2)[Cu12(DDPN)6(H2O)10Cl] (BUT-301) on shorter reaction time and (NH2(CH3)2)2[Cu(DDPN)] (BUT-302) on longer reaction time, when CuCl2 reacted with 3,5-di(3,5-dicarboxylphenyl)nitrobenzene (H4DDPN) in a DMA/MeOH mixed solvent at 120 °C. With increasing the reaction duration, BUT-301 can transform into BUT-302. Both MOFs have three-dimensional (3D) framework structures. BUT-301 is constructed from paddle-wheel Cu2(COO)4 units and DDPN4- ligands as four-connected linkers, while BUT-302 is assembled from mononuclear Cu(ii) centers connecting the ligands as also four-connected linkers but in a monodentate coordination fashion. N2 adsorption confirmed that both MOFs are porous materials with the Brunauer-Emmett-Teller (BET) surface areas of 1953 and 561 m2 g-1, respectively. Interestingly, both BUT-301 and -302 show selective adsorption properties of C3H4 over C3H6. The C3H4/C3H6 adsorption selectivities were calculated to be 1.9 and 4.4 at 0.1 bar and 298 K by the ideal adsorbed solution theory (IAST) for a 1 : 99 C3H4/C3H6 mixture, respectively.

Constructing new metal-organic frameworks with complicated ligands from "One-Pot" in situ reactions.

Metal-organic frameworks (MOFs) have emerged as one of the most fascinating libraries of porous materials. In spite of their myriad merits, practical application of most MOFs is restricted due to their high preparation cost because of the complicated organic ligands involved. To address this limitation, we propose to use simple and cheap organic precursors to synthesize MOFs with complicated ligands via "one-pot" in situ reactions of these precursors along with the formation of new MOFs. In this work, we have carefully screened several organic reactions, through which target ligands were generated in situ from easily available reactants during the MOF construction. With this "one-pot" approach, the fabrication of a series of novel MOFs by integrating the organic covalent bond and the coordinate bond has thus been realized through the judicious selection of organic reactions, which effectively simplifies the MOF synthesis process and thus reduces the cost.

A Stable Zr(IV)-Based Metal-Organic Framework Constructed from C═C Bridged Di-isophthalate Ligand for Sensitive Detection of Cr2O72- in Water.

As the Cr2O72- anion is highly toxic, new sensors have been developing for its effective detection from water, among which metal-organic frameworks (MOFs) show distinct superiority over many other materials. Herein, a new fluorescent Zr(IV)-based MOF, [Zr6O4(OH)8(H2O)4(sbtc)2] (referred to as BUT-28), based on the di-isophthalate ligand with a central CH═CH moiety, trans-stilbene-3,3',5,5'-tetracarboxylate (sbtc4-), has been prepared and structurally determined. The MOF shows excellent stability in neutral, highly acidic, and weakly basic aqueous solutions. Moreover, no essential uptake loss in three cycles of water vapor adsorption-desorption measurements was observed for BUT-28, suggesting the robustness of the porous framework and its great potential for long-term use. Fluorescent measurements were carried out for BUT-28 and an isostructural MOF, Zr-abtc, which is constructed from the di-isophthalate ligand with a central N═N moiety, azobenzene-3,3',5,5'-tetracarboxylate (abtc4-). Interestingly, Zr-abtc shows very weak fluorescent emission. In contrast, BUT-28 exhibits relatively strong fluorescence and serves as a promising sensory material for the detection of trace Cr2O72- (limit of detection: 36 ppb) in aqueous solutions by selective and sensitive fluorescence quenching effect.

Tuning Water Sorption in Highly Stable Zr(IV)-Metal-Organic Frameworks through Local Functionalization of Metal Clusters.

Water adsorption of metal-organic frameworks (MOFs) is attracting intense interest because of their potential applications in atmospheric water harvesting, dehumidification, and adsorption-based heating and cooling. In this work, through using a hexacarboxylate ligand, four new isostructural Zr(IV)-MOFs (BUT-46F, -46A, -46W, and -46B) with rare low-symmetric 9-connected Zr6 clusters were synthesized and structurally characterized. These MOFs are highly stable in water, HCl aqueous solution (pH = 1), and NaOH aqueous solution (pH = 10) at room temperature, as well as in boiling water. Interestingly, the rational modification of the metal clusters in these MOFs with different functional groups (HCOO-, CH3COO-, H2O/OH, and PhCOO-) enables the precise tuning of their water adsorption properties, which is quite important for given application. Furthermore, all four MOFs show excellent regenerability under mild conditions and good cyclic performance in water adsorption.