Periodic Reporting for period 3 - POPCRYSTAL (Precisely Oriented Porous Crystalline Films and Patterns)
Berichtszeitraum: 2021-05-01 bis 2022-10-31
Property-directional dependent (anisotropic) materials are commonly observed in nature and underpin essential structural and biological functions (e.g. wood, bones). Mankind has adopted this concept as the basis of important technologies such as microelectronic, visualization and lightning technologies, etc. Therefore, the discovery of protocols that can control structure-property relationship of functional materials are of significant technological interest.
Metal-Organic Frameworks (MOFs) are an emerging class of functional porous crystalline solids composed of organic linkers and inorganic nodes. Both linkers and nodes are chemically mutable and can be judiciously chosen and assembled into porous crystals where the bulk, the pores or the infiltration of guests could lead to new functional properties. These properties make MOFs highly desirable for technological applications, such as sensing electronics, and optics. However, the fabrication of MOF films and patterns with precisely aligned pores remains a major limitation for their application to devices.
The POPCRYSTAL project will investigate ceramic-to-MOF conversions for the fabrication of fully oriented nanoporous films and patterns. Crystalline ceramics (e.g. copper hydroxide, Cu(OH)2) will be used as substrates for the controlled growth of oriented, porous, crystalline films and patterns of MOFs (e.g. Copper-based MOFs, Cu-based MOFs). These novel platform materials will be employed for the fabrication of optically active devices.
Metal-Organic Frameworks (MOFs) are an emerging class of functional porous crystalline solids composed of organic linkers and inorganic nodes. Both linkers and nodes are chemically mutable and can be judiciously chosen and assembled into porous crystals where the bulk, the pores or the infiltration of guests could lead to new functional properties. These properties make MOFs highly desirable for technological applications, such as sensing electronics, and optics. However, the fabrication of MOF films and patterns with precisely aligned pores remains a major limitation for their application to devices.
The POPCRYSTAL project will investigate ceramic-to-MOF conversions for the fabrication of fully oriented nanoporous films and patterns. Crystalline ceramics (e.g. copper hydroxide, Cu(OH)2) will be used as substrates for the controlled growth of oriented, porous, crystalline films and patterns of MOFs (e.g. Copper-based MOFs, Cu-based MOFs). These novel platform materials will be employed for the fabrication of optically active devices.
Activities during the reported period:
1) Building up a team of young researchers.
2) Evaluation, selection, purchase, and setting up of equipment for the planned research activities. This included the purchase of an XRD, an AFM, and a Raman microscope. Improvements were made to existing equipment, (e.g. Dip Coater).
3) Since the project started, progress has been made on all WPs of POPCRYSTAL. The following points highlight the main studies and results so far:
a) the development of a protocol for the automatic deposition of aligned Cu(OH)2 nanobelts (NBs). This new method produces highly oriented samples with minimal variability. A manuscript that describes this protocol was published in Adv.Mat.Interf.
b) the understanding the key compositional variables for an optimized conversion from Cu(OH)2 NBs to aligned Cu-based MOF crystals is still in progress. Different variables such as type of organic solvent, amount of water as co-solvent, ligand concentration, and ceramic substrate pre-treatments were investigated (on-going). This activity has been substantially delayed by the COVID-19 pandemic; however, we have achieved some new discoveries. It was found that the variables that influence the oriented growth of the MOF films are the alignment of the Cu(OH)2 nanostructures and their pre-treatment to control their reactivity as feedstock materials in presence of the ligand for the Cu-MOF formation.
c) the use of different inorganic precursors and ligands to expand the scope of Cu-based MOFs:
We have studied how oriented Cu(OH)2 films can be converted in different Cu-based MOFs by using a variety of diverse carboxylic-acid functionalized linkers (L). For example, oriented MOFs films can be prepared by using: 1,4-naphthalenedicarboxylic acid; 2,6-naphthalenedicarboxylate; biphenyl-4,4’-dicarboxylic acid (BPDC) [Chem. Sci. 2020]; 2,5-dibromoterephthalic acid [submitted to Adv. Mat.].
We have converted Cu2(CO3)H2O into HKUST-1 (MOF) [R. Riccò et al. Chem.Mater. 2018]
We have transformed CuO into Cu-CDC and Cu-BDC MOFs [T. Stassin et al. Chem.Comm. 2019]
We have explored the conversion of ZnO membranes into ZIF-8 MOFs [R. Bo et al., Adv.Sci. 2020]. ZIF-8 was also produced in water in presence of proteins (ongoing research).
We have prepared MOF-on-MOF systems while maintaining the crystalline orientation of the different MOFs [K. Ikigaki et al. Angew.Chem. 2019]
d) Since the project started, we successfully fabricated 3 classes of MOF-based devices:
1. Optical switches (films and patterns) that allow for polarization-dependent optical responses. [Chem.Sci. 2020, Chem.Sci.2022 Adv.Mater. submitted]
2. A Li-S battery that used a 23 µm thick MOF separator as a perm-selective membrane. [Adv.Sci. 2020]
3. A gas sensor based on a MOF micro-pattern. [M. Tu et al., Nat.Mater. 2020]
Details and additional information are provided in the Scientific Report
1) Building up a team of young researchers.
2) Evaluation, selection, purchase, and setting up of equipment for the planned research activities. This included the purchase of an XRD, an AFM, and a Raman microscope. Improvements were made to existing equipment, (e.g. Dip Coater).
3) Since the project started, progress has been made on all WPs of POPCRYSTAL. The following points highlight the main studies and results so far:
a) the development of a protocol for the automatic deposition of aligned Cu(OH)2 nanobelts (NBs). This new method produces highly oriented samples with minimal variability. A manuscript that describes this protocol was published in Adv.Mat.Interf.
b) the understanding the key compositional variables for an optimized conversion from Cu(OH)2 NBs to aligned Cu-based MOF crystals is still in progress. Different variables such as type of organic solvent, amount of water as co-solvent, ligand concentration, and ceramic substrate pre-treatments were investigated (on-going). This activity has been substantially delayed by the COVID-19 pandemic; however, we have achieved some new discoveries. It was found that the variables that influence the oriented growth of the MOF films are the alignment of the Cu(OH)2 nanostructures and their pre-treatment to control their reactivity as feedstock materials in presence of the ligand for the Cu-MOF formation.
c) the use of different inorganic precursors and ligands to expand the scope of Cu-based MOFs:
We have studied how oriented Cu(OH)2 films can be converted in different Cu-based MOFs by using a variety of diverse carboxylic-acid functionalized linkers (L). For example, oriented MOFs films can be prepared by using: 1,4-naphthalenedicarboxylic acid; 2,6-naphthalenedicarboxylate; biphenyl-4,4’-dicarboxylic acid (BPDC) [Chem. Sci. 2020]; 2,5-dibromoterephthalic acid [submitted to Adv. Mat.].
We have converted Cu2(CO3)H2O into HKUST-1 (MOF) [R. Riccò et al. Chem.Mater. 2018]
We have transformed CuO into Cu-CDC and Cu-BDC MOFs [T. Stassin et al. Chem.Comm. 2019]
We have explored the conversion of ZnO membranes into ZIF-8 MOFs [R. Bo et al., Adv.Sci. 2020]. ZIF-8 was also produced in water in presence of proteins (ongoing research).
We have prepared MOF-on-MOF systems while maintaining the crystalline orientation of the different MOFs [K. Ikigaki et al. Angew.Chem. 2019]
d) Since the project started, we successfully fabricated 3 classes of MOF-based devices:
1. Optical switches (films and patterns) that allow for polarization-dependent optical responses. [Chem.Sci. 2020, Chem.Sci.2022 Adv.Mater. submitted]
2. A Li-S battery that used a 23 µm thick MOF separator as a perm-selective membrane. [Adv.Sci. 2020]
3. A gas sensor based on a MOF micro-pattern. [M. Tu et al., Nat.Mater. 2020]
Details and additional information are provided in the Scientific Report
WP1: Understanding – First objective: development of an automatic procedure for the deposition of reproducible films of aligned Cu(OH)2 nanobelts has been developed. With respect to the original manual transfer of the Cu(OH)2 precursor from a solution to a substrate, the automated process allows for the deposition of reproducible and highly aligned NBs films irrespective of the operator. This improvement is a key processing step since we have determined that the alignment of the MOF crystals in the films depends critically on the alignment of the precursor Cu(OH)2 NBs. The experimental study published, see M. Linares-Moreau et al., Adv.Mat.Interf. 2021. Sharing this protocol will help with the progress of this research field. - Second objective: understanding of the key compositional variables for the optimization of the conversion from Cu(OH)2 NBs to aligned Cu2(BDC)2 MOF crystals. We have performed preliminary in-situ and ex-situ studies of the conversion from Cu(OH)2 nanobelts to Cu-MOF with the AFM and SAXS to shed light on the underlying mechanisms that afford oriented MOF films. We believe that this study will help with the understanding of the conditions needed to apply the heteroepitaxial growth of MOFs to other systems.
WP2: Extension – We have been able to extend this ceramic-to-MOF concept to other materials, such as Cu2(CO3)H2O into HKUST-1, CuO into Cu-CDC and Cu-BDC MOFs, and ZnO into ZIF-8 monoliths. Additionally, the heteroepitaxial growth has been demonstrated for a multi-layer MOF-on-MOF approach creating complex composite materials. During this process, as described in the previous report, we found that ZnO can convert into ZIF-8 in presence of biomacromolecules. We think this is a very important discovery; indeed, the conversion occurs at room temperature without compromising the bio-activity of several tested biomacromolecules and this could be a key aspect for the fabrication of bio-hybrid devices. The investigation of different crystalline phases is ongoing to elucidate the properties of the different polymorphs of ZIF-8 when combined with biomacromolecules.
WP3: Control – A study was performed, with results suggesting that it is possible to tune on-demand the orientation of 1-D nanochannels on MOF films by changing the concentration of ligands and thus the acidity of the solution that induces different growth mechanisms which afford different orientation of the resulting MOF film: dissolution and precipitation growth mechanism (out of plane), or a heteroepitaxial growth mechanism (in-plane orientation).
WP4: Fabrication – The final fabrication of devices is in progress. The functional properties of the material are tested in devices as both films and patterns. In particular, optical, sensor, and separation devices have been fabricated and the protocol published (see previous point 2.d.1-2.d.3). Additional output is under development by combining the know-how from the different WPs.
WP2: Extension – We have been able to extend this ceramic-to-MOF concept to other materials, such as Cu2(CO3)H2O into HKUST-1, CuO into Cu-CDC and Cu-BDC MOFs, and ZnO into ZIF-8 monoliths. Additionally, the heteroepitaxial growth has been demonstrated for a multi-layer MOF-on-MOF approach creating complex composite materials. During this process, as described in the previous report, we found that ZnO can convert into ZIF-8 in presence of biomacromolecules. We think this is a very important discovery; indeed, the conversion occurs at room temperature without compromising the bio-activity of several tested biomacromolecules and this could be a key aspect for the fabrication of bio-hybrid devices. The investigation of different crystalline phases is ongoing to elucidate the properties of the different polymorphs of ZIF-8 when combined with biomacromolecules.
WP3: Control – A study was performed, with results suggesting that it is possible to tune on-demand the orientation of 1-D nanochannels on MOF films by changing the concentration of ligands and thus the acidity of the solution that induces different growth mechanisms which afford different orientation of the resulting MOF film: dissolution and precipitation growth mechanism (out of plane), or a heteroepitaxial growth mechanism (in-plane orientation).
WP4: Fabrication – The final fabrication of devices is in progress. The functional properties of the material are tested in devices as both films and patterns. In particular, optical, sensor, and separation devices have been fabricated and the protocol published (see previous point 2.d.1-2.d.3). Additional output is under development by combining the know-how from the different WPs.