Applied Science and Innovative Research ISSN 2474-4972 (Print) ISSN 2474-4980 (Online) Vol. 7, No. 2, 2023 www.scholink.org/ojs/index.php/asir 114 Original Paper Fluorescent Probes Based on Metal and Aggregation-Induced Emission Organic Molecule Complexes for Bioimaging and Sensing Applications Ke Liu1 1 College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China Received: April 16, 2023 Accepted: May 11, 2023 Online Published: May 12, 2023 doi:10.22158/asir.v7n2p114 URL: http://doi.org/10.22158/asir.v7n2p114 Abstract Metal-Organic Coordination polymer (MOCPs) is an emerging class of inorganic-organic porous hybrid materials with infinite coordination polymers (CPs) or metal-organic backbones (MOFs) formed by the interaction between metal ions and organic ligands and ligand functional groups. The molecular structure of the organic ligands composing MOCPs is rich in variation, while inorganic metal ions generally have good photoelectromagnetic properties. Therefore, MOCPs have diverse structural variations, adjustable pore size, high stability and controllable synthesis, and have received wide attention in gas storage, multiphase catalysis, chemical sensing and biological applications. Fluorescence properties are one of the most widely used techniques for bioimaging and sensing detection. However, conventional luminescent groups are usually affected by aggregation-induced quenching (ACQ) effects. Aggregation-induced luminescence molecules (AIEs) based on metal-organic coordination polymers combine the advantages of organic AIEs and transition metal centers to improve photophysical properties and therapeutic effects. 1. Aggregation-Induced Emission (AIE) 1.1 Introduction to Aggregation-Induced Emission The concept of aggregation-induced emission (AIE) was first proposed by Dr. Ben-Zhong Tang in 2001 (Luo et al., 2001). Since some solid molecules can also emit bright fluorescence in the dark environment, this phenomenon of fluorescence enhancement in the aggregated state is called AIE effect. Traditionally, some fluorescent groups in the solution state, such as rhodamine and coumarin, show strong fluorescence in the non-aggregated state, but when the concentration of these molecules www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 115 Published by SCHOLINK INC. becomes high or aggregation occurs, the fluorescence intensity of the molecules decreases or is directly burst, and the phenomenon exhibited by these molecules is called the aggregation-caused quenching (ACQ) effect. The excited states of aggregates of these molecules typically decay or relax back to the ground state as nonradiative channels, leading to the luminescence quenching of the luminescent groups. AIE molecules in contrast in the non-aggregated solution state, due to the existence of some AIE molecules can be free to move the structure, the molecular excited state is usually non-radiative channel decay or relaxation back to the ground state, the energy is dissipated almost no fluorescence, but in the aggregated state within the molecule movement is restricted, then the molecular excited state will be released in the form of radiation leap energy, making the molecule emit obvious fluorescence. Because the environment in the organism is mainly in the solution state, the AIE molecules entering the organism will fluoresce by aggregation in a specific microenvironment (Wang et al., 2013). AIE molecules also have the advantages of simple design and preparation, easy introduction of functional groups, and high luminescence intensity, so AIE effect-based fluorescent probes have good prospects for life science applications (Liang et al., 2014; Biju, 2014). In addition, the AIE-based fluorescent probes can be used for chemical sensing, bioimaging and drug transport (Yuan et al., 2015b; Xue et al., 2014; Mei et al., 2015). 1.2 Aggregation-Induced Emission Mechanism Elucidating the underlying mechanisms of the AIE phenomenon is important for exploring the fundamental principles of photophysics, but equally important, it can also be used to guide the design of new fluorescent molecules, explore practical applications, and promote technological innovation. Since the creation of the AIE concept in 2001, researchers have been exploring the real mechanisms responsible for the AIE phenomenon.. Firstly, based on the study of a common AIE molecule, hexaphenylsilole (HPS) (see Figure 1 for the molecular structure) (Leung et al., 2014), an restriction of intramolecular rotation (RIR) mechanism was proposed. In a close study of the HPS molecular structure, it was found that an HPS molecule is composed of a core of thiazole with six benzene rings attached to it by single bonds, and the large torsion angle between the thiazole as the core and the benzene rings surrounding it gives the HPS molecule a propeller-type flexible conformation. In the solid state, the large spatial repulsion between benzene rings makes it difficult for HPS molecules to stack in a face-to-face manner, and there is almost no π-π interaction between benzene rings of adjacent molecules, but the C-H···π non-covalent interaction between adjacent molecules makes HPS molecules aggregate and limits the free rotation of benzene rings. The non-radiative leap of HPS molecules in the aggregated state is therefore suppressed, and bright fluorescence can be produced. In addition to HPS molecules, substituted styrene molecules can also summarize the same luminescence mechanism, this intra-molecular group rotation is restricted in the way of RIR mechanism. However, the RIR mechanism does not apply to explain all AIE luminescence phenomena. In the structure of another common AIE molecule, bis-dibenzocycloheptane (THBA) (see Figure 1 for the molecular structure) (Viglianti et al., 2017), the symmetric aromatic ring structure in the molecule is held in place by a www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 116 Published by SCHOLINK INC. double bond that cannot rotate freely, but at this point the THBA molecule still has AIE properties, and a new mechanism is clearly needed to explain the luminescence of THBA. Because THBA molecules cannot dissipate energy by intra-molecular rotation, vibrational motion is the main way of energy consumption. Therefore, to explain the AIE phenomenon of THBA-like fluorescent molecules, the team of academician Ben-Zhong Tang also proposed the mechanism of restriction of intramolecular vibration (RIV). By combining RIR and RIV, it can be further summarized as the restriction of intramolecular motion (RIM) mechanism (Yao et al., 2014). Within a molecule there may be both groups that undergo rotational and vibrational motions, when the luminescence of the molecule is not determined by one of the RIR and RIV mechanisms alone, but both together produce the AIE effect. Figure 1. HPS Molecular Formula and Ball-and-stick Model (Leung et al., 2014) Figure 2. AIE Phenomenon Occurs in TPE due to RIR Mechanism; THBA in the Figure Below Shows the Existence of AIE Phenomenon due to RIV Mechanism (Viglianti et al., 2017) 2. Metal Organic Frameworks (MOFs) 2.1 Introduction to Metal Organic Frameworks (MOFs) Materials Metal-Organic Frameworks (MOFs) are an interesting class of crystalline porous materials that have received a great deal of attention from researchers and institutions in the past two decades. The first use of MOFs in 1995 (Yaghi & Li, 1995; Chan et al., 2012), since then, thousands of new MOFs with www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 117 Published by SCHOLINK INC. different sizes, shapes and structures have been reported (Li et al., 2012; Li et al., 2016). Since MOFs are self-assembled from metal ions or clusters and organic linkers through coordination bonds (Figure 3), they are highly designable and a wide range of possible structures exist. For example, MOFs can be designed to have large porosity (Furukawa et al., 2010) and a high specific surface area (Farha et al., 2012). It can reach 90% free volume and 7000 m2/g, respectively. In addition, the versatility of MOFs is fundamentally determined by their diverse structural and chemical properties, biocompatibility and biodegradability. Researchers have developed a large number of potential applications for MOFs, including gas storage and release (Mason et al., 2014), chemical separation (Li et al., 2012), catalysis (Lee et al., 2009), chemical separation (Li et al., 2012), catalysis (Lee et al., 2009), sensing and imaging (Deng et al., 2017; Shustova et al., 2012), drug delivery (Horcajada et al., 2006), drug delivery (Horcajada et al., 2006), removal of toxic substances (Mason et al., 2014; Howarth et al., 2015) etc. Currently, new MOFs materials with good stability are designed and synthesized based on different needs (Dong et al., 2020). The design and synthesis of new MOFs with good stability based on different needs (Dong et al., 2020) has become the focus of researchers to fully utilize their unique properties. Figure 3. Simplified Representation of Metal Organic Framework (MOF), Consisting of Metal Ions or Cluster Nodes and Organic Linkers 2.2 Synthesis of MOFs In 1995, Omar M. Yaghi and Hailian Li (Yaghi & Li, 1995) synthesized a crystalline material with a three-dimensional frame structure by solvothermal method using copper nitrate and 4,4 '-combo of methazas. The term "Metal OrganicFrameworks (MOF)" has been proposed to describe their composition and structural characteristics. Since then, these materials, which are formed by coordination and can be extended indefinitely at least in one dimension, have a fixed scientific name, laying the foundation for the subsequent development of these materials. With the continuous development of MOFs materials, some new synthetic methods such as grinding, ultrasonics, electrochemistry (Li et al., 2018; Dai et al., 2021; Stock & Biswas, 2012) have also emerged one after www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 118 Published by SCHOLINK INC. another, but currently the solvothermal method used by Omar M. Yaghi is still the mainstream method for the synthesis of MOFs materials. MOFs are a class of solid crystalline materials that link metal ions (or metal clusters) and organic ligands through coordination interactions. The selection of metals with coordination orbitals and atoms that can provide lone pairs of electrons is crucial for the successful synthesis of MOFs materials. In general, divalent (e.g., Zn2+, Cu2+, Co2+, Cd2+ ), trivalent (e.g., Fe3+, A13+, Cr3+ and most rare earth ions) and tetravalent metal ions (e.g., Zr4+, Ti4+, Ce4+ ) are often selected as nodes for coordination; ligands are also important factors for the structure, space, and synthesis conditions of MOFs during the construction of coordination bonds and the formation of framework structures, based on groups containing heteroatoms (N, O Based on the nature of heteroatom (N, O) containing groups that can usually be coordinated with metals, ligands containing cobordic acid, N heterocyclic, phosphoric acid and other groups are often chosen as linkage points for the construction of MOFs. In order to form spatially extensible structures, the number of these groups should be at least greater than two, and the complexity of their spatial structures will increase with the increase of the number of coordination groups, and their topology will change (Natarajan & Mahata, 2009). In addition, the backbone of the ligand usually contains a benzene ring structure to enhance its rigidity. In the process of synthesizing MOFs, in order to "customize" the structure of MOFs, direct (one-step) and indirect (multi-step) synthesis methods can be used, depending on the number of synthesis steps. Figure 4. Synthesis of Metal-organic Skeletal Compounds (Sharanyakanth & Radhakrishnan, 2020) www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 119 Published by SCHOLINK INC. 2.2.1 Direct Synthesis For coordination metal ions as described above, the desired target MOFs materials can be synthesized directly by heating reactions in solvent if suitable ligands are selected for coordination with them (Kalmutzki et al., 2018; Guillerm et al., 2014) The group of Omar M. Yaghi (Li et al., 1999) in 1999, MOF-5 was successfully synthesized using zinc nitrate as a metal salt, and its crystal structure contains Zn4O secondary building unit (SBU). On this basis, the group of Omar M. Yaghi (Deng et al., 2012) The researchers have also explored the synthesis of MOFs containing Zn4O structure with the same topology (Isoreticular Metal Organic Framework (IRMOF)) by fixing Zn metal salts and using different functionalized terephthalic acid or rigid ligands of different lengths of para-dicarboxylic acid. Taking Cr as an example, Ferey's research group (Serre et al., 2002) synthesized Cr-based MIL-53 (Materials of the Institute Lavoisier, MIL) in 2002, using terphenyl acid as a ligand. Its pore size can be regulated by hydration and dehydration. Subsequently, the research group directly synthesized MIL-100 (Horcajada et al., 2007) and MIL-101 (Ferey et al., 2005). with Fe and Cr as the metal center, respectively, and added hydrofluoric acid in the synthesis process, which believed that fluoride ions could induce crystal formation UiO-66 was used as a representative of the tetravalent metal Zr-based MOFs (Cavka et al., 2008; Zou & Liu, 2019), with Zr6O4(OH)4 as SBU, coordination with terephthalic acid forms a topology with a face centered cubic (FCC) lattice. In addition, the temperature required for the synthesis of metal-based MOFs differs for different valence states (Cheetham et al., 2018; Devic & Serre, 2014), generally higher temperatures (> 100 °C) are required for higher valence state metals (> 3+). For the synthesis of MOFs by solvothermal method, the solvent selection range is relatively wide, usually N,N '-dimethylformamide (DMF),N,N' -dimethylacetamide (DMAc),N,N '-diethylformamide (DEF) and other solvents with good solubility and high temperature stability are the preferred solvents, and mixed solvent systems can also be selected to improve the solubility (Howarth et al., 2017). 2.2.2 Indirect Synthesis Method In the actual synthesis process, the target MOFs may not be synthesized in one step due to factors such as reaction conditions, spatial site resistance, and the nature of the substance itself. In such cases, indirect synthesis methods are usually chosen to achieve the customization of functional materials of MOFs (Cui et al., 2019; Yuan et al., 2015a). This method first uses a direct method to synthesize MOFs that can be remodeled, and on this basis, the products are further reacted by chemical modification (Yin et al., 2019). Based on the structural characteristics of MOFs, post-modification can usually be performed by covalent post-modification for ligands or ligand-exchange post-modification for metals and ligands. The covalent post-modification is generally based on some common chemical reactions, and the reaction process should avoid MOF structure destruction. Therefore, mild and high conversion rate reactions during the modification process are often favored by the researchers. Limited by the poor thermal stability of the anatase skeleton, the group of Hongcai research group used a stepwise synthesis strategy to reserve an aldehyde reaction site in the skeleton of the synthesized MOF, and used this site www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 120 Published by SCHOLINK INC. to react with 1,2,3,3-tetramethyl-3H-iodinated indole salt to remodify the MOF. The cyanine was "installed" into the MOFs material, so as to realize the identification of cyanine (Li et al., 2020) (Figure 4). Yujun Zhao's group (Wang et al., 2019) The reaction of MOFs with salicylaldehyde and 2-bis(diphenylphosphino)benzaldehyde was based on the synthesis of MIL-101-NH2 using the Schiff base reaction, which provided ligand sites for the subsequent functionalization of ruthenium trichloride. The "click chemistry" reaction can also be applied to the covalent post-modification of MOFs due to its high reaction selectivity. (Goto et al., 2008) The crystals of the synthesized MOFs were immersed in a solution containing catalyst and terminal alkynes at 80°C for a period of time to obtain MOFs modified with different functional groups, taking advantage of the "click reaction" between azide and alkyne to form a five-membered ring. The results show that the modified MOFs still have a good crystalline shape. 3. Current Status of Domestic and International Research on Metal-organic Coordination Polymers The development and utilization of functional luminescent materials directly affects people's quality of life. As a kind of functional luminescent materials, metal-organic complex materials have attracted widespread attention in academia due to their unique optical properties. Currently, research on the use of metal-organic complexes as molecular fluorescent probes is flourishing. As a fluorescent probe, when metal-organic complexes are subjected to external influences or internal structural changes, they are output as fluorescent signals, which have the advantages of high sensitivity, good selectivity, low detection limit and fast response time, and can effectively improve the simplicity and intuitiveness of signal capture, and are widely used in the field of fluorescence identification of various substances. In conclusion, because metal-organic complex materials are constructed from inorganic metal ions and organic components, they have unique luminescence properties and a wide range of applications. 3.1 Bioimaging Chemical fluorescent probes have the advantages of simple testing, good selectivity, high sensitivity and convenient use, and can be used as a medium to detect and analyze substances in organisms. Due to the high sensitivity of the application of fluorescent probes in living organisms, the identification of trace amounts of substances in living organisms can be achieved, and a highly selective response can be achieved by modifying the fluorescent probes to exclude the interference of other substances. At the same time, the use of fluorescent probes does not require complicated steps, testing is convenient and fast, and without damaging biological samples, which helps researchers gain insight into the synthesis, localization, and biological roles of biomolecules in complex living systems, and is of great value in studying the physiological functions of important species within the living body. The development of fluorescent probes has simultaneously contributed to the progress of research in cell biology and medical diagnostics. In the past decades, various types of fluorescent probes have been synthesized and applied in bioimaging. www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 121 Published by SCHOLINK INC. Bioscopy can provide critical information for understanding various physiological and pathological processes, which is important for cancer screening and treatment, stem cell transplantation, etc. Many AIEs have strong resistance to photobleaching, high fluorescence quantum yields in the aggregated state, and good biocompatibility or low toxicity. These properties make them promising as biomaterials (Hu et al., 2014; Wang et al., 2010). Recently, many new AIE molecules have been designed and used to develop specific regions in cells. The design, photophysical properties and biological applications of existing probes allow localization imaging studies of mitochondria, lysosomes, nucleus, Golgi apparatus and endoplasmic reticulum, respectively (Zhu et al., 2014; Peng et al., 2011; Zhang et al., 2014). Intracellular pH (pHi ) is a fundamental factor controlling cellular behavior, such as cell division, apoptosis, ion transport, enzyme activity, and protein degradation. Tang's group (Chen et al., 2013) reported a pH-sensitive fluorophore, tetraphenylethen-cyanine (TPE-Cy), for pHi detection and tracking. It is biocompatible and cell-permeable. It enters cells by diffusion and is sensitive to the entire physiological range of pHi, being strongly red and blue emitting in acidic and alkaline, respectively. The red fluorescence of TPE-Cy varies with pH from strong to moderate between pH 5 -7 and from weak to absent between pH 7- 10. The usefulness of TPE-Cy for pHi development and monitoring was also demonstrated using confocal microscopy and ratiometric analysis. In addition, Liu et al. achieved two-color biomarkers using nanoprobes based on two AIE dyes (Li et al., 2013). 3.2 Chemical Sensors The sensing and detection of some metal ions in the environment is important for ecosystems. Some transition metal cations, such as Cu2+, Fe3+ and Fe2+, are essential in life processes, and the excess or deficiency of these metal cations during metabolism can lead to cause various diseases. Luminous metal organic complexes can also be used for the detection of metal ions. Du's group constructed Eu@UiO-MOFs for the efficient detection of Cd2+ with detection limits up to 5.67 × 10−7 M (114 ppb). Copper ion (Cu2+) is a typical micronutrient that has an important role in living systems. However, due to the frequent human activities, copper pollution in the ecosystem is becoming more and more serious, and long-term exposure to copper can lead to human toxicity. Liu's group prepared and synthesized ZIF-8@Rhodamine B for the detection of Cu2+ with a detection limit up to 22.8 nM. 4. Conclusion and Future Outlook In summary, metal-organic complexes have received increasing attention from scientists as a functional luminescent material with both inorganic and organic luminescent platforms. Currently, research on metal-organic complexes is not only limited to gas storage, separation and catalysis applications, but also the research on using metal-organic complexes as molecular fluorescent sensing materials is flourishing. As an emerging fluorescent sensing material, metal-organic complexes are output as fluorescent signals when they are subjected to external influences or internal structural changes, and have the advantages of high sensitivity, good selectivity, low detection limit and fast response, which www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 122 Published by SCHOLINK INC. can effectively improve the simplicity and intuitiveness of signal capture and are widely used in the field of fluorescence identification of various substances. However, the research of metal-organic complexes as fluorescent sensing materials for identification of substances is relatively single, and the identification mechanism is not explored deeply enough, mostly with the help of environmentally unfriendly organic solvents as the medium, and less research in aqueous solutions or low-toxic ethanol solutions, and the synthesis process is limited in yield, which greatly limits the scope of its practical application. Once a more complete understanding of the cellular behavior of metal-organic compounds is achieved, it is likely that metal-organic compounds will replace organic matter as biological probes in the near future, especially in applications where both their photophysical and biological properties can be exploited. Metal-organic compounds also offer great advantages over other drugs for combined imaging and therapy, providing a broad scope for metal-organic chemists to explore this relatively new field. References Biju, V. (2014). Chemical modifications and bioconjugate reactions of nanomaterials for sensing, imaging, drug delivery and therapy. Chemical Society Reviews, 43, 744-764. https://doi.org/10.1039/C3CS60273G Cavka, J. H., Jakobsen, S., Olsbye, U., et al. (2008). A new zirconium inorganic building brick forming metal organic frameworks with exceptional stability. Journal of the American Chemical Society, 130, 13850-13851. https://doi.org/10.1021/ja8057953 Chan, J., Dodani, S. C., & Chang, C. J. (2012). Reaction-based small-molecule fluorescent probes for chemoselective bioimaging. Nature Chemistry, 4, 973-984. https://doi.org/10.1038/nchem.1500 Cheetham, A. K., Kieslich, G., & Yeung, H. H. M. (2018). Thermodynamic and Kinetic Effects in the Crystallization of Metal-Organic Frameworks. Accounts of Chemical Research, 51, 659-667. https://doi.org/10.1021/acs.accounts.7b00497 Chen, S., Hong, Y., Liu, Y., et al. (2013). Full-Range Intracellular pH Sensing by an Aggregation-Induced Emission-Active Two-Channel Ratiometric Fluorogen. Journal of the American Chemical Society, 135, 4926-4929. https://doi.org/10.1021/ja400337p Cui, P., Wang, P., Zhao, Y., et al. (2019). Fabrication of Desired Metal-Organic Frameworks via Postsynthetic Exchange and Sequential Linker Installation. Crystal Growth & Design, 19, 1454-1470. https://doi.org/10.1021/acs.cgd.8b01628 Dai, S., Nouar, F., Zhang, S., et al. (2021). One-Step Room-Temperature Synthesis of Metal(IV) Carboxylate Metal-Organic Frameworks. Angewandte Chemie- International Edition, 60, 4282-4288. https://doi.org/10.1002/anie.202014184 Deng, H., Grunder, S., Cordova, K. E., et al. (2012). Large-Pore Apertures in a Series of Metal-Organic Frameworks. Science, 336, 1018-1023. https://doi.org/10.1126/science.1220131 www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 123 Published by SCHOLINK INC. Deng, Y., Chen, N., Li, Q., et al. (2017). Highly Fluorescent Metal-Organic Frameworks Based on a Benzene-Cored Tetraphenylethene Derivative with the Ability To Detect 2,4,6-Trinitrophenol in Water. Crystal Growth & Design, 17, 3170-3177. https://doi.org/10.1021/acs.cgd.7b00131 Devic, T., & Serre, C. (2014). High valence 3p and transition metal based MOFs. Chemical Society Reviews, 43, 6097-6115. https://doi.org/10.1039/C4CS00081A Dong, J., Pan, Y., Wang, H., et al. (2020). Self-Assembly of Highly Stable Zirconium(IV) Coordination Cages with Aggregation Induced Emission Molecular Rotors. Angewandte Chemie-International Edition, 59, 10151-10159. https://doi.org/10.1002/anie.201915199 Farha, O. K., Eryazici, I., Jeong, N. C., et al. (2012). Metal-Organic Framework Materials with Ultrahigh Surface Areas: Is the Sky the Limit? Journal of the American Chemical Society, 134, 15016-15021. https://doi.org/10.1021/ja3055639 Ferey, G., Mellot-Draznieks, C., Serre, C., et al. (2005). A chromium terephthalate-based solid with unusually large pore volumes and surface area. Science, 309, 2040-2042. https://doi.org/10.1126/science.1116275 Furukawa, H., Ko, N., Go, Y. B., et al. (2010). Ultrahigh Porosity in Metal-Organic Frameworks. Science, 329, 424-428. https://doi.org/10.1126/science.1192160 Goto, Y., Sato, H., Shinkai, S., et al. (2008). "Clickable" Metal-Organic Framework. Journal of the American Chemical Society, 130, 14354-14355. https://doi.org/10.1021/ja7114053 Guillerm, V., Kim, D., Eubank, J. F., et al. (2014). a supermolecular building approach for the design and construction of metal-organic frameworks. Chemical Society Reviews, 43, 6141-6172. https://doi.org/10.1039/C4CS00135D Horcajada, P., Serre, C., Vallet-Regi, M., et al. (2006). Metal-organic frameworks as efficient materials for drug delivery. Angewandte Chemie-International Edition, 45, 5974-5978. https://doi.org/10.1002/anie.200601878 Horcajada, P., Surble, S., Serre, C., et al. (2007). Synthesis and catalytic properties of MIL-100(Fe), an iron(III) carboxylate with large pores. Chemical Communications, 2820-2822. https://doi.org/10.1039/B704325B Howarth, A. J., Liu, Y., Hupp, J. T., et al. (2015). Metal-organic frameworks for applications in remediation of oxyanion/cation-contaminated water. Crystengcomm, 17, 7245-7253. https://doi.org/10.1039/C5CE01428J Howarth, A. J., Peters, A. W., Vermeulen, N. A., et al. (2017). Best Practices for the Synthesis, Activation, and Characterization of Metal-Organic Frameworks. Chemistry of Materials, 29, 26-39. https://doi.org/10.1021/acs.chemmater.6b02626 Hu, R., Leung, N. L. C., & Tang, B. Z. (2014). AIE macromolecules: syntheses, structures and functionalities. Chemical Society Reviews, 43, 4494-4562. https://doi.org/10.1039/C4CS00044G Kalmutzki, M. J., Hanikel, N., & Yaghi, O. M. (2018). secondary building units as the turning point in the development of the reticular chemistry of MOFs. Science Advances, 4. www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 124 Published by SCHOLINK INC. https://doi.org/10.1126/sciadv.aat9180 Lee, J., Farha, O. K., Roberts, J., et al. (2009). Metal-organic framework materials as catalysts. Chemical Society Reviews, 38, 1450-1459. https://doi.org/10.1039/b807080f Leung, N. L. C., Xie, N., Yuan, W., et al. (2014). Restriction of Intramolecular Motions: The General Mechanism behind Aggregation-Induced Emission. Chemistry-a European Journal, 20, 15349-15353. https://doi.org/10.1002/chem.201403811 Li, D., Feng, Y., Lin, J., et al. (2016). A mitochondria-targeted two-photon fluorescent probe for highly selective and rapid detection of hypochlorite and its Sensors and Actuators. B-Chemical, 222, 483-491. https://doi.org/10.1016/j.snb.2015.08.098 Li, H., Eddaoudi, M., O'keeffe, M., et al. (1999). Design and synthesis of an exceptionally stable and highly porous metal-organic framework. Nature, 402, 276-279. https://doi.org/10.1038/46248 Li, J.-R., Sculley, J., & Zhou, H.-C. (2012). Metal-Organic Frameworks for Separations. Chemical Reviews, 112, 869-932. https://doi.org/10.1021/cr200190s Li, J., Yuan, S., Qin, J.-S., et al. (2020). Stepwise Assembly of Turn-on Fluorescence Sensors in Multicomponent Metal-Organic Frameworks for in Vitro Cyanide Detection. Angewandte Chemie-International Edition, 59, 9319-9323. https://doi.org/10.1002/anie.202000702 Li, K., Zhu, Z., Cai, P., et al. (2013). Organic Dots with Aggregation-Induced Emission (AIE Dots) Characteristics for Dual-Color Cell Tracing. Chemistry of Materials, 25, 4181-4187. https://doi.org/10.1021/cm401709d Li, P., Cheng, F.-F., Xiong, W.-W., et al. (2018). New synthetic strategies to prepare metal-organic frameworks. Inorganic Chemistry Frontiers, 5, 2693-2708. https://doi.org/10.1039/C8QI00543E Liang, G., Lam, J. W. Y., Qin, W., et al. (2014). Molecular luminogens based on restriction of intramolecular motions through host-guest inclusion for cell imaging. Chemical Communications, 50, 1725-1727. https://doi.org/10.1039/C3CC48625G Luo, J. D., Xie, Z. L., Lam, J. W. Y., et al. (2001). Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole. Chemical Communications, 1740-1741. https://doi.org/10.1039/b105159h Mason, J. A., Veenstra, M., & Long, J. R. (2014). Evaluating metal-organic frameworks for natural gas storage. Chemical Science, 5, 32-51. https://doi.org/10.1039/C3SC52633J Mei, J., Leung, N. L. C., Kwok, R. T. K., et al. (2015). Aggregation-Induced Emission: Together We Shine, United We Soar! Chemical Reviews, 115, 11718-11940. https://doi.org/10.1021/acs.chemrev.5b00263 Natarajan, S., & Mahata, P. (2009). Metal-organic framework structures - how closely are they related to classical inorganic structures? Chemical Society Reviews, 38, 2304-2318. https://doi.org/10.1039/b815106g Peng, X., Wu, T., Fan, J., et al. (2011). An Effective Minor Groove Binder as a Red Fluorescent Marker for Live-Cell DNA Imaging and Quantification. Angewandte Chemie-International Edition, 50, www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 125 Published by SCHOLINK INC. 4180-4183. https://doi.org/10.1002/anie.201007386 Serre, C., Millange, F., Thouvenot, C., et al. (2002). Very large breathing effect in the first nanoporous chromium(III)-based solids: MIL-53 or Cr-III(OH) center dot{O2C-C6H4-CO2}center dot{HO2C-C6H4-CO2H}(x)center dot H2Oy. Journal of the American Chemical Society, 124, 13519-13526. https://doi.org/10.1021/ja0276974 Sharanyakanth, P. S., & Radhakrishnan, M. (2020). Synthesis of metal-organic frameworks (MOFs) and its application in food packaging: a critical review. Trends in Food Science & Technology, 104, 102-116. https://doi.org/10.1016/j.tifs.2020.08.004 Shustova, N. B., Ong, T.-C., Cozzolino, A. F., et al. (2012). Phenyl Ring Dynamics in a Tetraphenylethylene-Bridged Metal-Organic Framework: Implications for the Mechanism of Aggregation-Induced Emission. Journal of the American Chemical Society, 134, 15061-15070. https://doi.org/10.1021/ja306042w Stock, N., & Biswas, S. (2012). Synthesis of Metal-Organic Frameworks (MOFs): Routes to Various MOF Topologies, Morphologies, and Composites. Chemical Reviews, 112, 933-969. https://doi.org/10.1021/cr200304e Viglianti, L., Leung, N. L. C., Xie, N., et al. (2017). Aggregation-induced emission: mechanistic study of the clusteroluminescence of tetrathienylethene. Chemical Science, 8, 2629-2639. https://doi.org/10.1039/C6SC05192H Wang, M., Zhang, G., Zhang, D., et al. (2010). Fluorescent bio/chemosensors based on silole and tetraphenylethene luminogens with aggregation-induced. Journal of Materials Chemistry, 20, 1858-1867. https://doi.org/10.1039/b921610c Wang, S., Hou, S., Wu, C., et al. (2019). RuCl3 anchored onto post-synthetic modification MIL-101(Cr)-NH2 as heterogeneous catalyst for hydrogenation of CO2 to Chinese Chemical Letters, 30, 398-402. https://doi.org/10.1016/j.cclet.2018.06.021 Wang, Y., Yan, B., & Chen, L. (2013). SERS Tags: Novel Optical Nanoprobes for Bioanalysis. Chemical Reviews, 113, 1391-1428. https://doi.org/10.1021/cr300120g Xue, X., Zhao, Y., Dai, L., et al. (2014). Spatiotemporal Drug Release Visualized through a Drug Delivery System with Tunable Aggregation-Induced Emission. Advanced Materials, 26, 712-717. https://doi.org/10.1002/adma.201302365 Yaghi, O. M., & Li, H. L. (1995). Hydrothermal Synthesis of a Metal-Organic Framework Containing Large Rectangular Channels. Journal of the American Chemical Society, 117, 10401-10402. https://doi.org/10.1021/ja00146a033 Yao, L., Zhang, S., Wang, R., et al. (2014). Highly Efficient Near-Infrared Organic Light-Emitting Diode Based on a Butterfly-Shaped Donor-Acceptor Chromophore with Strong Solid-State Fluorescence and a Large Proportion of Radiative Excitons. Angewandte Chemie-International Edition, 53, 2119-2123. https://doi.org/10.1002/anie.201308486 Yin, Z., Wan, S., Yang, J., et al. (2019). Recent advances in post-synthetic modification of www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 2, 2023 126 Published by SCHOLINK INC. metal-organic frameworks: new types and tandem reactions. Coordination Chemistry Reviews, 378, 500-512. https://doi.org/10.1016/j.ccr.2017.11.015 Yuan, S., Lu, W., Chen, Y.-P., et al. (2015a). Sequential Linker Installation: Precise Placement of Functional Groups in Multivariate Metal-Organic Frameworks. Journal of the American Chemical Society, 137, 3177-3180. https://doi.org/10.1021/ja512762r Yuan, Y., Zhang, C.-J., & Liu, B. (2015b). A Photoactivatable AIE Polymer for Light-Controlled Gene Delivery: Concurrent Endo/Lysosomal Escape and DNA Unpacking. Angewandte Chemie-International Edition, 54, 11419-11423. https://doi.org/10.1002/anie.201503640 Zhang, S., Fan, J., Li, Z., et al. (2014). A bright red fluorescent cyanine dye for live-cell nucleic acid imaging, with high photostability and a large Stokes shift. Journal of Materials Chemistry B, 2, 2688-2693. https://doi.org/10.1039/C3TB21844A Zhu, H., Fan, J., Wang, J., et al. (2014). An "Enhanced PET"-Based Fluorescent Probe with Ultrasensitivity for Imaging Basal and Elesclomol-Induced HClO in Cancer Cells. Journal of the American Chemical Society, 136, 12820-12823. https://doi.org/10.1021/ja505988g Zou, D., & Liu, D. (2019). Understanding the modifications and applications of highly stable porous frameworks via UiO-66. Materials Today Chemistry, 12, 139-165. https://doi.org/10.1016/j.mtchem.2018.12.004