Development of metal-organic frameworks for biomedical applications - a review

Metal-organic frameworks (MOFs) are porous materials made from coordination bonding of organic linkers and metal nodes. Nowadays, MOFs have already achieved a considerable growth in many fields including in bio-related applications. In this review, we focus on the alternative, green route of MOFs synthesis as well as their toxicological properties. We also highlighted the potential of MOFs as therapeutic agents and nano-MOFs (NMOFs) for biomedical sensing. Water as an alternative media for MOF synthesis showed excellent results in term of particle size, stability and selectivity. Toxicological assessments revealed Fe (III) and MIL-100 as the most promising metal and MOF for medical applications. It was also shown that MOFs are sensitive towards physiological and pathological criteria such as pH, fluorescence and O2. Although many attempts have been made in utilizing MOFs for bio applications, further improvements should be considered before MOFs can become effective therapeutics options

Exploring the Potential of a Highly Scalable Metal-Organic Framework CALF-20 for Selective Gas Adsorption at Low Pressure

In this study, the ability of the highly scalable metal-organic framework (MOF) CALF-20 to adsorb polar and non-polar gases at low pressure was investigated using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The results from the simulated adsorption isotherms revealed that the highest loading was achieved for SO2 and Cl2, while the lowest loading was found for F2 molecules. The analysis of interaction energies indicated that SO2 molecules were able to form the strongest adsorbent-adsorbate interactions and had a tight molecular packing due to their polarity and angular structure. Additionally, Cl2 gas was found to be highly adsorbed due to its large van der Waals surface and strong chemical affinity in CALF-20 pores. MD simulations showed that SO2 and Cl2 had the lowest mobility inside CALF-20 pores. The values of the Henry coefficient and isosteric heat of adsorption confirmed that CALF-20 could selectively adsorb SO2 and Cl2. Based on the results, it was concluded that CALF-20 is a suitable adsorbent for SO2 and Cl2 but not for F2. This research emphasizes the importance of molecular size, geometry, and polarity in determining the suitability of a porous material as an adsorbent for specific adsorbates

Elucidating the aromatic properties of covalent organic frameworks surface for enhanced polar solvent adsorption

Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 and covalent triazine-based frameworks (CTF-1), are studied. In addition, a theoretical porous graphene (TPG) was included for comparison purposes. The three solid sheets were investigated for aromaticity and stability using quantum mechanics calculations and their ability for water and ethanol adsorption using molecular dynamics simulations. COF-1 demonstrated the poorest aromatic character due to the highest energy delocalization interaction between B–O bonding orbital of sigma type and unfilled valence-shell nonbonding of boron. CTF-1 was identified as the least kinetically stable and the most chemically reactive. Both COF-1 and CTF-1 showed good surface properties for selective adsorption of water via hydrogen bonding and electrostatic interactions. Among the three sheets, TPG’s surface was mostly affected by aromatic currents and localized π electrons on the phenyl rings which in turn made it the best platform for selective adsorption of ethanol via van der Waals interactions. These results can serve as guidelines for future studies on solvent adsorption for COFs materials

Exploring the Potential of a Highly Scalable Metal-Organic Framework CALF-20 for Selective Gas Adsorption at Low Pressure

In this study, the ability of the highly scalable metal-organic framework (MOF) CALF-20 to adsorb polar and non-polar gases at low pressure was investigated using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The results from the simulated adsorption isotherms revealed that the highest loading was achieved for SO2 and Cl2, while the lowest loading was found for F2 molecules. The analysis of interaction energies indicated that SO2 molecules were able to form the strongest adsorbent-adsorbate interactions and had a tight molecular packing due to their polarity and angular structure. Additionally, Cl2 gas was found to be highly adsorbed due to its large van der Waals surface and strong chemical affinity in CALF-20 pores. MD simulations showed that SO2 and Cl2 had the lowest mobility inside CALF-20 pores. The values of the Henry coefficient and isosteric heat of adsorption confirmed that CALF-20 could selectively adsorb SO2 and Cl2. Based on the results, it was concluded that CALF-20 is a suitable adsorbent for SO2 and Cl2 but not for F2. This research emphasizes the importance of molecular size, geometry, and polarity in determining the suitability of a porous material as an adsorbent for specific adsorbates

Rational design of different π-bridges and their theoretical impact on indolo[3,2,1-jk] carbazole based dye-sensitized solar cells

Eight new π-bridges for a promising indolo[3,2,1-jk] carbazole based dye IC-2 were rationally designed. In the first set of derivatives, π-bridges consisting of thiophene, furan and pyrrole ring were constructed. The bridges were then extended with additional heterocyclic ring linked together with either ethylene or azo moiety. Their structural, electronic, optical and photovoltaic properties were evaluated based on density functional theory calculation. π-Bridges containing furan ring and azo moiety were the most planar and demonstrated smaller HOMO and LUMO gap. Extended furan π-bridge with azo group exhibited the lowest excitation energy and broadest UV-Vis absorption peaks. Large values of the light harvesting ability were observed for all extended π-bridges while pyrrole π-bridges resulted in the highest value of open circuit voltage. Based on these properties, the extended compounds would be good candidates for DSSC and further investigation on dye@TiO2 complex systems is warranted

Calcium L-Malate and D-Tartarate Frameworks as Adjuvants for the Sustainable Delivery of Fungicide

Agrichemical adjuvants that combine a highly selective, efficient, and active mode of operation are critically needed to realize a more sustainable approach to their usage. Herein, we report the synthesis and full characterization of two new metal-organic frameworks (MOFs), termed UPMOF-1 and UPMOF-2, that were constructed from eco-friendly Ca2+ ions and naturally-occurring, low molecular weight plant acids, L-malic and D-tartaric acid, respectively. Upon structural elucidation of both MOFs, a widely-used fungicide, hexaconazole (Hex), was loaded on the structures reaching binding affinities of -5.0 and -3.5 kcal mol-1 and loading capacities of 63 and 62% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively, as a result of the formation of stable host-guest interactions. Given the MOFs’ framework chemistry and predisposition to disassembly in relevant agricultural conditions, the sustained release kinetics were determined to show near quantitative release (98 and 95% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively) after >500 h – a release profile drastical-ly different than the control (>80% release in 24 h), from which the high efficiency of these new systems was established. To confirm their high selectivity and activity, in vitro and in vivo studies were performed to illustrate the abilities of Hex@UPMOF-1 and Hex@UPMOF-2 to combat the known, aggressive pathogen Ganoderma boninense (G. boninense) that causes basal stem rot disease in oil palm. Accordingly, at an extremely low concentration of 0.05 μg mL-1, both Hex@UPMOF-1 and Hex@UPMOF-2 were demonstrated to completely inhibit (100%) G. boninense growth and during a 26-week in vivo nursery trial, the progression of basal stem rot infection was not only completely halted upon treatment with Hex@UPMOF-1 and Hex@UPMOF-2, but seedling growth accelerated given the additional nutrients supplied via the disassembly of the MOFs. This study represents a significant step forward in designing adjuvants to support the environ-mentally responsible use of agrichemical crop protection