Peer-reviewed Publications (summary)

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Among multivariate metal‚Äďorganic frameworks, multivariate modulated (MTVM) MOFs offer the possibility of introducing multiple functionalised units into the MOFs as defect-compensating ligands promoting porosity among other defect-related properties. However, there are no studies that rationalise the incorporation of multiple functionalised modulators and their resultant properties, hindering their molecular design and multi-applicability. In this manuscript, we introduce up to five functionalised modulators bearing NO2, F,¬†tBu, OH and NH2¬†units in significant quantities (up to¬†ca. 31 mol%) into the Ti heterometallic MOF MUV-10 in one-pot synthesis, increasing the porosity by up to¬†ca. 1.3-fold in comparison with the pristine material. We have rationalised the incorporation ratios of the different combinations of modulators among other properties. As a proof-of-concept, we have shown that there is up to a 1.7-fold enhancement in the catalytic activity of MTVM MOFs for the regioselective opening of epoxides, anticipating that this protocol can be used to produce multi-functionalised materials with a wide range of applications.

¬†I. Ab√°nades L√°zaro; R. S. Forgan and F. G. Cirujano ¬ęMOF nanoparticles as heterogeneous catalysts for direct amide bond formations¬Ľ,¬†Dalton Transactions, 2022,¬†51, 8368-8376.

The influence of composition and textural characteristics of a family of ultra-small isoreticular UiO-type metal‚Äďorganic frameworks (MOFs) with different functionalized and extended linkers on their catalytic performance is evaluated. Two direct amide bond formations across four different substrates (benzylamine + phenylacetic acid and aniline + formic acid) are employed as proof-of-concept reactions to test the activity of the Zr-MOF nanoparticles. The reaction rates of amide bond formation are evaluated against physico-chemical properties such as crystallinity, porosity, particle size or linker functionality, alongside the Lewis acid and hydrophobic properties of the MOFs, in order to gain insights into the catalytic mechanism and optimal properties for its enhancement.

¬†I. Ab√°nades L√°zaro,¬†H. Szalad, P. Valiente, J. Albero, H. Garc√≠a, C. Mart√≠-Gastaldo, ¬ęTuning the Photocatalytic Activity of Ti-Based Metal‚ÄďOrganic Frameworks through Modulator Defect-Engineered Functionalization¬Ľ¬†ACS Appl. Mater. Interfaces,¬†2022, 14, 18, 21007‚Äď21017.

 We report a comprehensive study on the defect engineering of the titanium heterometallic MOF MUV-10 by fluoro- and hydroxy-isophthalic acid (Iso) modulators, rationalizing the effect of the materials’ properties on their photocatalytic activity for hydrogen production. The Iso-OH modified MOFs present a volcano-type profile with a 2.3-fold increase in comparison to the pristine materials, whereas the Iso-F modified samples have a gradual increase with up to a 4.2-fold enhancement.  The higher photocatalytic activity in Iso-F modulator derived MOF has been attributed to the effect of the divergent defect-compensation modes on the materials’ photostability and to the increase in the external surface area upon introduction of Iso-F modulator.

¬†I. Ab√°nades L√°zaro; J. M. Rodrigo-Mu√Īoz;¬†B. Sastre; ¬†M. Romero √Āngel; C. Marti-Gastaldo; V. del Pozo ¬ęThe excellent biocompatibility and negligible immune response of the titanium heterometallic MOF MUV-10¬Ľ,¬†Journal of Materials Chemistry B,¬†2021, 9, 6144-6148.¬†Front Cover

The Ti‚ÄďCa heterometallic MOF MUV-10 exhibits good dispersibility in phosphate buffer and low phosphate-induced degradation in comparison to other MOF systems. It induces no cytotoxicity towards cells of the immune system and no inmune response, making it an attractive candidate for biomedical applications and demonstrating its safe use for other applications.

I. Ab√°nades L√°zaro; C. Popescu and F. G. Cirujano ¬ęControlling the molecular diffusion in MOFs with the acidity of monocarboxylate modulators¬Ľ,¬†Dalton Transactions, 2021, 50, 11291-11299.

 We show that the molar percent of defects, either as missing linkers or as a part of missing cluster defects, is related to the acidity of a modulator and its subsequent incorporation into the UiO-66 structure. Modulators with strong acidity and small size result in a considerable defect induction that causes an increase in the external surface area and mesopore volume, which is beneficial for the ring-opening of epoxides with amines, using UiO-66 defect-modulated MOFs as heterogeneous catalysts.

¬†I. Ab√°nades L√°zaro, N. Almora-Barrios, S. Tatay and C. Mart√≠-Gastaldo.¬ĽEffect of modulator connectivity on promoting defectivity in titanium-organic frameworks¬Ľ Chemical Science,2021,¬†12, 2586-2593

 We report a systematic study on the ability of mono- and dicarboxylic modulators (benzoic and isophthalic acid) to promote defect creation in the heterometallic Ti-MOF of the MUV-10 family. Our results indicate that both acids behave as capping modulators at high concentrations, but isophthalic acid is a more efficient defect promoter, yielding defective phases with nearly 40% of missing linkers. Our computational results suggest that this difference cannot be solely ascribed to relative changes in acidity but to the ability of this bidentate linker in compensating the structural distortion and energy penalty imposed by breaking the connectivity of the underlying framework.

I. Ab√°nades L√°zaro, N. Almora-Barrios, Sergio Tatay , C. Popescu, C. Mart√≠-Gastaldo,¬ĽLinker depletion for missing cluster defects in non-UiO metal‚Äďorganic frameworks¬Ľ,¬†Chemical Science, 2021, 12, 11839-11844.

We describe the preferential formation of missing cluster defects in heterometallic titanium‚Äďorganic frameworks of the MUV-10 family when synthesised in sub-stoichiometric linker conditions.¬† Correlation of experiment with computational models reveals the dominance of missing cluster vacancies in the pore size distribution of defective MUV-10. These same models were used to investigate the correlation of defects by synchrotron X-ray diffraction. The diffraction at low reflection angles is dominated by diffuse scattering that is indicative of short-range order and cannot be indexed to the defective structural models generated. In addition to the low atomic scattering factor of titanium, these results confirm the need for high-resolution electron microscopy methods for modelling nanoscale disorder in titanium MOFs.

The literature-reported methods to characterise the composition of MOF materials are revised, and a new multifaceted TGA methodology to determine the exact composition of MOFs is presented. An example applicable to any defective MOF is provided, with specific examples for the most common MOFs. This methodology is applied to multicomponent MOFs, mixtures of MOFs and MOF composites using UiO-66 as an example.

Presentation of results in conferences Conferences

2022 ‚ÄėCoordination modulation of Metal-Organic Frameworks for defect-controlled multivariate structures for enhanced applications‚Äô, MOF2022, Dresden (Germany).

2021 ‚ÄėDefect chemistry of Titanium MOFs‚Äô I. Ab√°nades L√°zaro, WISC, Cagliari (Italy).

2019 ‚ÄėDefect chemistry of Titanium Metal-Organic Frameworks‚Äô I. Ab√°nades L√°zaro and C. Marti-Gastaldo, Spanish Royal Society of Chemistry Young Investigators Symposium (University of Valencia) ‚ÄďOral presentation.

2019 ‚ÄėDefect chemistry of Zirconium and Titanium Metal-Organic Frameworks‚Äô I. Ab√°nades L√°zaro and C. Marti-Gastaldo, EuroMOF2019, Paris (France) ‚Äď Poster presentation.

2019 ‚ÄėDefect chemistry of Zirconium and Titanium Metal-Organic Frameworks‚Äô I. Ab√°nades L√°zaro and C. Marti-Gastaldo, 1st workshop of young researchers in Chemistry (University of Valencia) ‚ÄďOral presentation.

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