The release of anthropogenic toxic pollutants into the atmosphere is a worldwide threat of growing concern. In this regard, it is possible to take advantage of the high versatility of MOFs materials ...in order to develop new technologies for environmental remediation purposes. Consequently, one of the main scientific challenges to be achieved in the field of MOF research should be to maximize the performance of these solids towards the sensing, capture and catalytic degradation of harmful gases and vapors by means of a rational control of size and reactivity of the pore walls that are directly accessible to guest molecules.
Tunable hydrophobicity: Efficient air filters for the protection against chemical warfare agents might be achieved by surface functionalization of the pores in robust metal–organic frameworks (MOFs) ...with fluoroalkyl residues and the precise control of their pore size (see picture). These MOFs capture harmful volatile organic compounds even under extremely moist conditions (80 % relative humidity).
The current technology of air‐filtration materials for protection against highly toxic chemicals, that is, chemical‐warfare agents, is mainly based on the broad and effective adsorptive properties of ...hydrophobic activated carbons. However, adsorption does not prevent these materials from behaving as secondary emitters once they are contaminated. Thus, the development of efficient self‐cleaning filters is of high interest. Herein, we report how we can take advantage of the improved phosphotriesterase catalytic activity of lithium alkoxide doped zirconium(IV) metal–organic framework (MOF) materials to develop advanced self‐detoxifying adsorbents of chemical‐warfare agents containing hydrolysable PF, PO, and CCl bonds. Moreover, we also show that it is possible to integrate these materials onto textiles, thereby combining air‐permeation properties of the textiles with the self‐detoxifying properties of the MOF material.
The silk of human kindness: Insertion of lithium alkoxides in zirconium metal–organic frameworks (MOF) which are then deposited on silk fibers gives rise to protective fabrics capable of self‐detoxifying chemical‐warfare agents. The fabrics combine the air‐permeation properties of the textiles with the highly active phosphotriesterase catalytic activity of the MOF for the hydrolysis of PF, PO, and CCl bonds.
The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of ...isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects.
This work describes synthesis at the nanoscale of the isoreticular metal-organic framework (MOF) series ZnBDP_X, based on the assembly of Zn(II) metal ions and the functionalized organic spacers ...1,4-bis(1H-pyrazol-4-yl)-2-X-benzene (H2BDP_X; X = H, NO2, NH2, OH). The colloidal stability of these systems was evaluated under different relevant intravenous and oral-simulated physiological conditions, showing that ZnBDP_OH nanoparticles exhibit good structural and colloidal stability probably because of the formation of a protein corona on their surface that prevents their aggregation. Furthermore, two antitumor drugs (mitroxantrone and Ru(p-cymene)Cl2(pta) (RAPTA-C) where pta = 1,3,5-triaza-7-phospaadamantane) were encapsulated within the pores of the ZnBDP_X series in order to investigate the effect of the framework functionalization on the incorporation/delivery of bioactive molecules. Thus, the loading capacity of both drugs within the ZnBDP_X series seems to directly depend on the surface area of the solids. Moreover, ligand functionalization significantly affects both the delivery kinetics and the total amount of released drug. In particular, ZnBDP_OH and ZnBDP_NH2 matrixes show a slower rate of delivery and higher percentage of release than ZnBDP_NO2 and ZnBDP_H systems. Additionally, RAPTA-C delivery from ZnBDP_OH is accompanied by a concomitant and progressive matrix degradation due to the higher polarity of the BPD_OH ligand, highlighting the impact of functionalization of the MOF cavities over the kinetics of delivery.
The ionic conductivity properties of the face‐centered cubic Ni8(OH)4(H2O)2(BDP_X)6 (H2BDP_X=1,4‐bis(pyrazol‐4‐yl)benzene‐4‐X with X=H (1), OH (2), NH2 (3)) metal–organic framework (MOF) systems as ...well as their post‐synthetically modified materials KNi8(OH)5(EtO)(BDP_X)5.5 (1@KOH, 3@KOH) and K3Ni8(OH)3(EtO)(BDP_O)5 (2@KOH), which contain missing‐linker defects, have been studied by variable temperature AC impedance spectroscopy. It should be noted that these modified materials exhibit up to four orders of magnitude increase in conductivity ‐values in comparison to pristine 1–3 systems. As an example, the conductivity value of 5.86×10−9 S cm−1 (activation energy Ea of 0.60 eV) for 2 at 313 K and 22 % relative humidity (RH) increases up to 2.75×10−5 S cm−1 (Ea of 0.40 eV) for 2@KOH. Moreover, a further increase of conductivity values up to 1.16×10−2 S cm−1 and diminution of Ea down to 0.20 eV is achieved at 100 % RH for 2@KOH. The increased porosity, basicity and hydrophilicity of the 1@KOH–3@KOH materials compared to the pristine 1–3 systems should explain the better performance of the KOH‐modified materials.
The missing link: The deliberate introduction of defects on fcu frameworks by KOH/EtOH, leading to missing‐linker defects and metal cluster basification, is responsible for a boosting of the ion conductivity and depletion of activation energy.
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This work is a critical preventive study for providing a healthy life and enhancing people's safety at work in which introduces of highly efficient and durable UV-protection and ...antibacterial textiles. With this aim, ZnO nanoparticles are in situ synthesized on the modified cotton fabric to produce the multifunctional fabrics. Herein, the cotton fabric is oxidized by periodate and then treated by 4-aminobenzoic acid ligand (PABA). The modified cotton fabrics are characterized via X-ray powder diffraction, Fourier-transform infrared spectroscopy-attenuated total reflectance, scanning electron microscope, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Moreover, the anti-bacterial, UV-protection, hydrophilicity, and mechanical properties of samples are investigated. The results show that pre-oxidization cotton fabric provides better active sites for the treatment with PABA. Then, PABA treatment provides significant sites for the growth of the ZnO nanoparticles and maintains cross-linking property between oxidized cellulosic fibers and the ZnO nanoparticles which improves the formation and durability of ZnO nanoparticles. The simultaneous sample treatment with ZnO and PABA had synergistic effects on UV protection, stability, and mechanical properties. Moreover, the ZnO PABA oxidized cotton fabrics show excellent UV-protection and significant antibacterial efficacy after 20 washing cycles and 100 abrasion cycles, which can be used in advanced protective textiles.
In this communication, a series of observations and data analyses coherently confirms the suitability of the novel metal-organic framework (MOF) ...Zn(4)(μ(4)-O)(μ(4)-4-carboxy-3,5-dimethyl-4-carboxy-pyrazolato)(3) (1) in the capture of harmful volatile organic compounds (VOCs). It is worthy of attention that 1, whose crystal structure resembles that of MOF-5, exhibits remarkable thermal, mechanical, and chemical stability, as required if practical applications are sought. In addition, it selectively captures harmful VOCs (including models of Sarin and mustard gas, which are chemical warfare agents), even in competition with ambient moisture (i.e., under conditions mimicking operative ones). The results can be rationalized on the basis of Henry constant and adsorption heat values for the different essayed adsorbates as well as H(2)O/VOC partition coefficients as obtained from variable-temperature reverse gas chromatography experiments. To further strengthen the importance of 1, its performance in the capture of harmful VOCs has been compared with those of well-known materials, namely, a MOF with coordinatively unsaturated metal sites, Cu(3)(btc)(2) and the molecular sieve active carbon Carboxen. The results of this comparison show that coordinatively unsaturated metal sites (preferential guest-binding sites) are ineffective for the capture of VOCs in the presence of ambient moisture. Consequently, we propose that the driving force of the VOC-MOF recognition process is mainly dictated by pore size and surface hydrophobicity.
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