Periodic Reporting for period 4 - POPCRYSTAL (Precisely Oriented Porous Crystalline Films and Patterns)
Berichtszeitraum: 2022-11-01 bis 2024-07-31
Materials with properties that vary along specific geometric directions, also called 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 microelectronics, 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 investigates ceramic-to-MOF conversions for the fabrication of fully oriented nanoporous films and patterns. Crystalline ceramics (e.g. copper hydroxide, Cu(OH)2) are 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 is 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 investigates ceramic-to-MOF conversions for the fabrication of fully oriented nanoporous films and patterns. Crystalline ceramics (e.g. copper hydroxide, Cu(OH)2) are 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 is employed for the fabrication of optically active devices.
Activities during the reported period (overview of the whole project):
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, and all the main objectives have been now completed. The following points highlight the main results:
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. 2021.
b) the understanding of the key compositional variables for an optimized conversion from Cu(OH)2 NBs to aligned Cu-based MOF crystals. This investigation allowed us to develop protocols for 12 heteroepitaxially oriented MOF film systems. Selected outcomes: Chem.Sci. 2020, 11, 8005; Advanced Materials 2023,35, 2211478; Adv. Mater. Interfaces 2023, 10, 2202461; Chemical Science 2023, 14, 12056; Advanced Materials 2024, 2309645.
c) The extension of POPCRYSTAL through the use of chemically functionalized ligands to tune functional properties of MOFs. The conversion of Cu(OH)2 nanobelts to Cu2(L)2(DABCO) MOFs (using different ligands, e.g. L= BDC, 1,4-NDC, 2,6-NDC, Br2BDC, BPDC, N3BPDC) was investigated. Importantly, the halogen (Br-) and azide (N3-) functional groups endowed the MOF films with photosensitive properties used for patterning and cross-linking. Outcomes: Adv. Mater., 2023,35, 2211478; Adv. Mater. 2024, 2404384.
d) Since the project started, we successfully fabricated different classes of MOF-based devices. Below we highlight some of them:
d1) 3D-oriented fluorescent MOF micropatterns with anisotropic optical response and diffraction-grating properties. Adv. Mater. 2023, 2211478.
d2) 3D-oriented fluorescent polymer micropatterns with anisotropic optical response (photonic applications) and superior chemical stability. Adv. Mater. 2024, 2404384.
d3) MOF-based printed photoluminescent oxygen sensor. Adv. Mater. 2024, 202408770.
d4) A colorimetric biogenic amine sensor printed on flexible substrates to monitor food decomposition. Adv. Mater. 2024, 202408770.
d5) A 23 µm thick MOF as a separator membrane in a Li-S battery. Adv.Sc. 2020.
d6) A vapor sensor based on a MOF micro-pattern. Nat.Mater. 2020.
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, and all the main objectives have been now completed. The following points highlight the main results:
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. 2021.
b) the understanding of the key compositional variables for an optimized conversion from Cu(OH)2 NBs to aligned Cu-based MOF crystals. This investigation allowed us to develop protocols for 12 heteroepitaxially oriented MOF film systems. Selected outcomes: Chem.Sci. 2020, 11, 8005; Advanced Materials 2023,35, 2211478; Adv. Mater. Interfaces 2023, 10, 2202461; Chemical Science 2023, 14, 12056; Advanced Materials 2024, 2309645.
c) The extension of POPCRYSTAL through the use of chemically functionalized ligands to tune functional properties of MOFs. The conversion of Cu(OH)2 nanobelts to Cu2(L)2(DABCO) MOFs (using different ligands, e.g. L= BDC, 1,4-NDC, 2,6-NDC, Br2BDC, BPDC, N3BPDC) was investigated. Importantly, the halogen (Br-) and azide (N3-) functional groups endowed the MOF films with photosensitive properties used for patterning and cross-linking. Outcomes: Adv. Mater., 2023,35, 2211478; Adv. Mater. 2024, 2404384.
d) Since the project started, we successfully fabricated different classes of MOF-based devices. Below we highlight some of them:
d1) 3D-oriented fluorescent MOF micropatterns with anisotropic optical response and diffraction-grating properties. Adv. Mater. 2023, 2211478.
d2) 3D-oriented fluorescent polymer micropatterns with anisotropic optical response (photonic applications) and superior chemical stability. Adv. Mater. 2024, 2404384.
d3) MOF-based printed photoluminescent oxygen sensor. Adv. Mater. 2024, 202408770.
d4) A colorimetric biogenic amine sensor printed on flexible substrates to monitor food decomposition. Adv. Mater. 2024, 202408770.
d5) A 23 µm thick MOF as a separator membrane in a Li-S battery. Adv.Sc. 2020.
d6) A vapor sensor based on a MOF micro-pattern. Nat.Mater. 2020.
Despite the delays and re-scheduling of the project activities, and thanks to the extensions granted, the project has progressed according to the planned scheme. We have succeeded with all WPs and delivered outcomes along all the main lines of the original proposal. In the following, we detail the main outcomes of each WP:
WP1: Understanding – First objective: an automatic procedure for the deposition of reproducible films of aligned Cu(OH)2 nanobelts has been developed. This new procedure greatly improved the homogeneity, reproducibility and orientation of the ceramic films and subsequently of the MOF films. We conducted studies on various compositional variables affecting MOF conversion, identifying pH, ligand concentration, and substrate pre-treatment as key factors, which allowed us to optimize the synthesis protocols for 12 heteroepitaxially oriented new MOF films.
We also conducted ex-situ and in-situ studies of the hydrolytic stability and degradation kinetics of Cu-based MOFs. We identified conditions where MOFs degrade rapidly in high humidity or water, revealing stability challenges for practical application, motivating our progress in WP2 and WP3 to develop functionalized MOFs with improved stability.
WP2: Extension – We have developed a high throughput computational screening to identify Cu-based MOFs that have the correct crystalline and chemical features to produce aligned heteroepitaxial MOFs grown on Cu(OH)2.
We have succeeded in using chemically functionalized ligands to tune functional properties of MOFs. We converted Cu(OH)2 nanobelts to Cu2(L)2(DABCO) MOFs (using different ligands, e.g. L= BDC, 1,4-NDC, 2,6-NDC, Br2BDC, BPDC, N3BPDC). We obtained 12 different MOF films systems with heteroepitaxial 3D-orientation grown on Cu(OH)2 nanobelts. Importantly, the halogen (Br-) and azide (N3-) functional groups endowed the MOF films with photosensitive properties, later used for patterning and cross-linking.
We have also been able to extend this ceramic-to-MOF concept to other materials, such as Cu2(CO3)H2O, CuO, and ZnO. Additionally, the heteroepitaxial growth has been demonstrated for a multi-layer MOF-on-MOF approach creating complex composite materials.
WP3: Control – We developed protocols for the controlled fabrication of high-quality heteroepitaxially oriented MOF films (see WP1) and high-quailty micropatterns. We developed the fabrication of micropatterns of 3D oriented Cu2(L)2DABCO MOF films by using X-ray sensitive organic linkers (L= Br2BDC). Further, using azide-functionalized linkers, we were able to obtain oriented porous polymer (CL-POL) micropatterns starting from the MOF Cu2(N3BPDC)2DABCO by X-ray lithography. These CL-POL micropatterns preserve the original orientation, with the advantage of superior chemical and structural stability.
WP4: Fabrication – We have fabricated different MOF-based devices, which we highlighted in the previous point. In particular, we highlight the development of novel MOF-patterning technologies, and the fabrication of MOF-templated porous polymer micropatterns, which have great potential to extend the realm of applications for MOFs increasing their chemical stability. The patterning methods were used to fabricate different kinds of sensors and optical devices.
Details and additional information are provided in the final Periodic Report (RP4) and Scientific Report.
WP1: Understanding – First objective: an automatic procedure for the deposition of reproducible films of aligned Cu(OH)2 nanobelts has been developed. This new procedure greatly improved the homogeneity, reproducibility and orientation of the ceramic films and subsequently of the MOF films. We conducted studies on various compositional variables affecting MOF conversion, identifying pH, ligand concentration, and substrate pre-treatment as key factors, which allowed us to optimize the synthesis protocols for 12 heteroepitaxially oriented new MOF films.
We also conducted ex-situ and in-situ studies of the hydrolytic stability and degradation kinetics of Cu-based MOFs. We identified conditions where MOFs degrade rapidly in high humidity or water, revealing stability challenges for practical application, motivating our progress in WP2 and WP3 to develop functionalized MOFs with improved stability.
WP2: Extension – We have developed a high throughput computational screening to identify Cu-based MOFs that have the correct crystalline and chemical features to produce aligned heteroepitaxial MOFs grown on Cu(OH)2.
We have succeeded in using chemically functionalized ligands to tune functional properties of MOFs. We converted Cu(OH)2 nanobelts to Cu2(L)2(DABCO) MOFs (using different ligands, e.g. L= BDC, 1,4-NDC, 2,6-NDC, Br2BDC, BPDC, N3BPDC). We obtained 12 different MOF films systems with heteroepitaxial 3D-orientation grown on Cu(OH)2 nanobelts. Importantly, the halogen (Br-) and azide (N3-) functional groups endowed the MOF films with photosensitive properties, later used for patterning and cross-linking.
We have also been able to extend this ceramic-to-MOF concept to other materials, such as Cu2(CO3)H2O, CuO, and ZnO. Additionally, the heteroepitaxial growth has been demonstrated for a multi-layer MOF-on-MOF approach creating complex composite materials.
WP3: Control – We developed protocols for the controlled fabrication of high-quality heteroepitaxially oriented MOF films (see WP1) and high-quailty micropatterns. We developed the fabrication of micropatterns of 3D oriented Cu2(L)2DABCO MOF films by using X-ray sensitive organic linkers (L= Br2BDC). Further, using azide-functionalized linkers, we were able to obtain oriented porous polymer (CL-POL) micropatterns starting from the MOF Cu2(N3BPDC)2DABCO by X-ray lithography. These CL-POL micropatterns preserve the original orientation, with the advantage of superior chemical and structural stability.
WP4: Fabrication – We have fabricated different MOF-based devices, which we highlighted in the previous point. In particular, we highlight the development of novel MOF-patterning technologies, and the fabrication of MOF-templated porous polymer micropatterns, which have great potential to extend the realm of applications for MOFs increasing their chemical stability. The patterning methods were used to fabricate different kinds of sensors and optical devices.
Details and additional information are provided in the final Periodic Report (RP4) and Scientific Report.