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.
Two isoreticular series of pyrazolate-based 3D open metal–organic frameworks, MBDP_X, adopting the NiBDP and ZnBDP structure types H2BDP = 1,4-bis(1H-pyrazol-4-yl)benzene, were synthesized with the ...new tagged organic linkers H 2 BDP_X (X = −NO2, −NH2, −OH). All of the MBDP_X materials have been characterized through a combination of techniques. IR spectroscopy proved the effective presence of tags, while X-ray powder diffraction (XRPD) witnessed their isoreticular nature. Simultaneous TG/DSC analyses (STA) demonstrated their remarkable thermal stability, while variable-temperature XRPD experiments highlighted their high degree of flexibility related to guest-induced fit processes of the solvent molecules included in the channels. A structural isomer of the parent NiBDP was obtained with a sulfonate tagged ligand, H 2 BDP_SO 3 H. Structure solution from powder diffraction data collected at three different temperatures (room temperature, 90, and 250 °C) allowed the determination of its structure and the comprehension of its solvent-related flexible behavior. Finally, the potential application of the tagged MOFs in selective adsorption processes for gas separation and purification purposes was investigated by conventional single component adsorption isotherms, as well as by advanced experiments of pulse gas chromatography and breakthrough curve measurements. Noteworthy, the results show that functionalization does not improve the adsorption selectivity (partition coefficients) for the resolution of gas mixtures characterized by similar high quadrupole moments (e.g., CO2/C2H2); however, the resolution of gas mixtures containing molecules with highly differentiated polarities (i.e., N2/CO2 or CH4/CO2) is highly improved.
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 development of protective self-detoxifying materials is an important societal challenge to counteract risk of attacks employing highly toxic chemical warfare agents (CWAs). In this work, we have ...developed bifunctional zirconium metal–organic frameworks (MOFs) incorporating variable amounts of nucleophilic amino residues by means of formation of the mixed ligand Zr6O4(OH)4(bdc)6(1–x)(bdc-NH2)6x (UiO-66-xNH 2 ) and Zr6O4(OH)4(bpdc)6(1–x)(bpdc-(NH2)2)6x (UiO-67-x(NH 2 ) 2 ) systems where bdc = benzene-1,4-dicarboxylate; bdc-NH2= benzene-2-amino-1,4-dicarboxylate; bpdc = 4,4′-biphenyldicarboxylate; bpdc-(NH2)2 = 2,2′-diamino-4,4′-biphenyldicarboxylate and x = 0, 0.25, 0.5, 0.75, 1. In a second step, the UiO-66-xNH 2 and UiO-67-x(NH 2 ) 2 systems have been postsynthetically modified by introduction of highly basic lithium tert-butoxide (LiO t Bu) on the oxohydroxometallic clusters of the mixed ligand MOFs to yield UiO-66-xNH 2 @LiO t Bu and UiO-67-x(NH 2 ) 2 @LiO t Bu materials. The results show that the combination of pre and postsynthetic modifications on these MOF series gives rise to fine-tuning of the catalytic activity toward the hydrolytic degradation of both simulants and real CWAs in unbuffered aqueous solutions. Indeed, UiO-66-0.25NH 2 @LiO t Bu is able to hydrolyze both CWAs simulants (diisopropylfluorophosphate (DIFP), 2-chloroethylethylsulfide (CEES), and real CWAs (soman (GD), sulfur mustard (HD)) quickly in aqueous solution. These results are related to a suitable combination of robustness, nucleophilicity, basicity, and accessibility to the porous framework.
Aluminum-based metal–organic frameworks (MOFs), Al(OH)(SDC) n , (H2SDC: 4,4′-stilbenedicarboxylic acid), also known as CYCU-3, were prepared by means of the coordination modulation method to ...produce materials with different crystal size and morphology. In particular, we screened several reagent concentrations (20–60 mM) and modulator/ligand ratios (0–50), leading to 20 CYCU x_y materials (x: reagent concentration, y = modulator/ligand ratio) with different particle size and morphology. Noteworthy, the use of high modulator/ligand ratio gives rise to a new phase of CYCU-3 (CYCU-3′ x_50 series), which was structurally analyzed. Afterward, to test the potential of these materials as CO-prodrug carriers, we selected three of them to adsorb the photo- and bioactive CO-releasing molecule (CORM) ALF794 Mo(CNCMe2CO2H)3(CO)3 (CNCMe2CO2H = 2-isocyano-2-methyl propionic acid): (i) CYCU-3 20_0, particles in the nanometric range; (ii) CYCU-3 50_5, bar-type particles with heterogeneous size, and (iii) CYCU-3′ 50_50, a new phase analogous to pristine CYCU-3. The corresponding hybrid materials were fully characterized, revealing that CYCU-3 20_0 with the smallest particle size was not stable under the drug loading conditions. Regarding the other two materials, similar ALF794 loadings were found (0.20 and 0.19 CORM/MOF molar ratios for ALF794@CYCU-3 50_5 and ALF794@CYCU-3′ 50_50, respectively). In addition, these hybrid systems behave as CO-releasing materials (CORMAs), retaining the photoactive properties of the pristine CORM in both phosphate saline solution and solid state. Finally, the metal leaching studies in solution confirmed that ALF794@CYCU-3′ 50_50 shows a good retention capacity toward the potentially toxic molybdenum fragments (75% of retention after 72 h), which is the lowest value reported for a MOF-based CORMA to date.
Mesoporous silica Al-MCM-41 nanoparticles have been used, for the first time, as vehicles for the single and dual encapsulation of the cationic CO-releasing molecule (CORM) ...Mn(1,4,7-triazacyclononane)(CO)3+ (ALF472+) and the well-known antineoplastic drug, cis-PtCl2(NH3)2 (cisplatin). Thus, two new hybrid materials, namely, ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41, have been isolated and fully characterized. The results reveal that the presence of CORM molecules enhances cisplatin loading 3-fold, yielding a cargo of 0.45 mmol g–1 of ALF472+ and 0.12 mmol g–1 of the platinum complex for ALF472-cisplatin@Al-MCM-41. It is worth noting that ALF472@Al-MCM-41 shows a good dispersion in phosphate buffered saline solution, while the dual hybrid material slightly aggregates in this simulated physiological medium (hydrodynamic size: 112 ± 23 and 336 ± 50 nm, respectively). In addition, both hybrid materials (ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41) behave as photoactive CO-releasing materials, delivering 0.25 and 0.11 equiv of CO, respectively, after 24 h and exhibiting a more controlled CO delivery than that of the free CORM. Finally, metal leaching studies have confirmed the good retention capacity of Al-MCM-41 toward the potentially toxic manganese fragments (86% of retention after 72 h) as well as the low release of cisplatin (ca. 7% after 72 h).
The reaction of (cymene)RuCl22 with K2Hoxonate (H3oxonic = 4,6-dihydroxy-2-carboxy-1,3,5-triazine acid) in methanol leads to the formation of the dinuclear half-sandwich ruthenium(II) complex ...(cymene)2Ru2(μ-Hoxonato)Cl2 (1a). Removal of the chloride ligands of 1a by treatment with AgCF3SO3 yields (cymene)2Ru2(μ-Hoxonato)(CF3SO3)2 (1b), which, upon posterior reaction with N,N′-linkers (L = 4,4′-bipyridine (4,4′-bpy), 4,7-phenantroline (4,7-phen)), gives rise to the formation of the tetranuclear open boxes (cymene)4Ru4(μ-Hoxonato)2(μ-N,N′-L)2(CF3SO3)4 (2a, L = 4,4′-bpy; 2b, L = 4,7-phen). These systems have been characterized by 1H NMR, UV−vis, and ESI-MS. The single-crystal structures of the dinuclear precursor 1a and of the clathrate 2b⊂4,7-phen have been determined. The interaction of these systems with cysteine, mononucleotides, and calf-thymus DNA has been studied by means of 1H NMR, UV−vis, circular dicroism, competitive binding assays, and atomic force microscopy imaging. The results show that the robust tetracationic ruthenium(II) cyclic systems 2a and 2b do not give ligand exchange reactions toward biorelevant ligands. Nevertheless, these systems are able to noncovalently bind to DNA, probably at the surface of the major groove, inducing significant conformational changes in this biomolecule. It is also interesting to note that compounds 2a and 2b, in spite of only giving supramolecular interactions with biomolecules, exhibit antitumor activity, particularly toward the human ovarian cancer cell line A2780cisR, showing acquired resistance to cisplatin, with respective 4.6 and 8.3 microM IC50 values.
A novel ultramicroporous coordination polymer, namely Cu(F-pymo)2(H2O)1.25 n (1, F-pymo = 5-fluoropyrimidin-2-olate), has been prepared and structurally characterized. 1 displays a zeolitic ...gismondine (GIS) topology, with ca. 2.9 Å wide helical channels which, in the thermally activated counterpart (1‘), account for a 13% void volume and are responsible for the observed selective solid−gas adsorption properties toward H2, N2, and CO2. At 77 K 1‘ behaves as a molecular sieve, selectively adsorbing H2 over N2, possibly due to size-exclusion reasons. At variance, although CO2 molecules are slightly larger than the pore size, they are readily incorporated by 1‘ at temperatures as high as 433 K. Variable-temperature X-ray powder diffraction (TXRPD) studies, in the temperature range 303−473 K, show that dehydration is reversible and has almost negligible effects on the network. At variance, the uptake of CO2 occurs through a transient phase and channels expansion. While the gas storage capacity of 1‘ is not very highH2, 0.56 wt % and 0.010 kg H2/L at 90 K and 900 Torr, and CO2, 7.6 wt % at 273 K and 900 Torrthe guest molecules achieve very high densities, comparable to that of the liquid for H2 (0.023 vs 0.021 molecules Å-3) and to that of the solid for CO2 (0.014 vs 0.022 molecules Å-3). In addition, we have also studied the effect of the perturbation exerted by the guest molecules on its magnetic properties. The results show that while dehydration of 1 has negligible effect on its spin-canted antiferromagnetic behavior, CO2 incorporation in the pores is responsible for an increment of the transition temperature at which the weak ferromagnetic ordering takes place from 22 to 29 K.
H2, N2, CO, and CO2 are readily incorporated in the porous, 3D sodalitic frameworks of coordination polymers of the ML2 n type, with M = PdII or CuII and HL = 2-hydroxypyrimidine or ...4-hydroxypyrimidine. The metal ion and ligand functionalization modulate their sorption properties, making these materials suitable for gas storage and separation purposes.
The highly porous and robust Ni(8)(OH)(4)(OH(2))(2)(4,4'-(buta-1,3-diyne-1,4-diyl)bispyrazolato)(6)(n) MOF can be used as a proof of concept for the incorporation and release of the non-conventional ...Ru(p-cymene)Cl(2)(pta) RAPTA-C metallodrug.
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