Turn-On Fluorescence in Tetraphenylethylene-Based Metal–Organic Frameworks: An Alternative to Aggregation-Induced Emission

Abstract

Coordinative immobilization of functionalized tetraphenylethylene within rigid porous metal-organic frameworks (MOFs) turns on fluorescence in the typically non-emissive tetraphenylethylene core. The matrix coordination-induced emission effect (MCIE) is complementary to aggregation-induced emission. Despite the large interchromophore distances imposed by coordination to metal ions, a carboxylate analogue of tetraphenylethylene anchored by Zn(2+) and Cd(2+) ions inside MOFs shows fluorescence lifetimes in line with those of close-packed molecular aggregates. Turn-on fluorescence by coordinative ligation in a porous matrix is a powerful approach that may lead to new materials made from chromophores with molecular rotors. The potential utility of MCIE toward building new sensing materials is demonstrated by tuning the fluorescence response of the porous MOFs as a function of adsorbed small analytes.

Coordination-induced reversible electrical conductivity variation in the MOF-74 analogue Fe2(DSBDC)

“…The electronic properties may be modulated either inherently, through changes in chemical composition, or through hostguest interactions. Guest molecules may cause structural variation, 8,9 tune electrical conductivity, 10,11 induce spin state transitions, 12,13 modulate luminescence wavelength, 14,15 and even participate in guest-guest interactions. 16 These phenomena are of fundamental interest and form the basis of various applications including chemiresistive sensors, 11,17,18 fluorescence sensors, 19 and cooperative adsorption.…”

Design of Highly Photofunctional Porous Polymer Films with Controlled Thickness and Prominent Microporosity

“…Conventional AIE-based polymers function with as ensitivity of several hundreds of parts per million. [5] However,t he polyTPECz films with at hickness of 5nm also retained outstanding selectivity for TMP over DNP, DNT,NP, and NT (see Figures S11 and S12).…”

“…Notably,t he luminescence activity of the porous polyTPECz films is the highest reported for AIEbased porous materials to date;these materials typically have aquantum yield of only afew percent (see Table S1). [5] Owing to their cross-linked nature,the polyTPECz films were robust and retained their luminescence in common organic solvents and various aqueous acidic and basic solutions,t hus making them useful as luminescent materials for applications under different conditions.…”

“…[5] However,t hese porous solids are less emissive and lack processability (see Table S1 in the Supporting Information). [5] In this study,w ei ntroduced the concept of AIE to the design of POP networks through the use of acomplementary design scheme.Inconjunction with the electropolymerization method, we succeeded in the first synthesis of highly luminescent photofunctional POP films.T oe stablish the properties of high emission and photoactivity,w ei ntegrated AIE units into the focal core of the p-system (Figure 1a, green part of TPECz), whereas multiple peripheral units (blue parts) were designed for site-specific electropolymerization, and phenylene linkers (purple parts) were employed to introduce twists that help the development of threedimensional porous skeletons (Figure 1b,c). Theelectropolymerization of N-substituted carbazoles was established as ap olymerization method several decades ago.N evertheless, this method was not developed until recently for the synthesis of POP films.…”

Synthesis, crystal structures and photocatalytic properties of four silver(I) coordination polymers based on semirigid bis(pyrazole) and carboxylic acid co-ligands

“…The crystal engineering of supramolecular architectures based on metal and mixed organic building blocks has attracted much attention, owing to their fascinating network topologies, as well as potential applications in various fields such as catalysis [1], luminescence [2], gas storage [3], molecular magnetism [4] and ion exchange [5]. In contrast to other transition metals, Ag(I) has a tendency to display highly versatile and irregular coordination numbers and geometries (linear, trigonal, tetrahedral, square planar and square pyramidal) because of its stable d 10 closed-shell electronic configuration.…”