Engineered Bifunctional Luminescent Pillared‐Layer Frameworks for Adsorption of CO₂ and Sensitive Detection of Nitrobenzene in Aqueous Media

Abstract

Through a dual‐ligand synthetic approach, five isoreticular primitive cubic (pcu)‐type pillared‐layer metal–organic frameworks (MOFs), [Zn2(dicarboxylate)2(NI‐bpy‐44)]⋅x DMF⋅y H2O, in which dicarboxylate=1,4‐bdc (1), Br‐1,4‐bdc (2), NH2‐1,4‐bdc (3), 2,6‐ndc (4), and bpdc (5), have been engineered. MOFs 1–5 feature twofold degrees of interpenetration and have open pores of 27.0, 33.6, 36.8, 52.5, and 62.1 %, respectively. Nitrogen adsorption isotherms of activated MOFs 1′–5′ at 77 K all displayed type I adsorption behavior, suggesting their microporous nature. Although 1′ and 3′–5′ exhibited type I adsorption isotherms of CO2 at 195 K, MOF 2′ showed a two‐step gate‐opening sorption isotherm of CO2. Furthermore, MOF 3′ also had a significant influence of amine functions on CO2 uptake at high temperature due to the CO2–framework interactions. MOFs 1–5 revealed solvent‐dependent fluorescence properties; their strong blue‐light emissions in aqueous suspensions were efficiently quenched by trace amounts of nitrobenzene (NB), with limits of detection of 4.54, 5.73, 1.88, 2.30, and 2.26 μm, respectively, and Stern–Volmer quenching constants (Ksv) of 2.93×103, 1.79×103, 3.78×103, 4.04×103, and 3.21×103 m−1, respectively. Of particular note, the NB‐included framework, NB@3, provided direct evidence of the binding sites, which showed strong host–guest π–π and hydrogen‐bonding interactions beneficial for donor–acceptor electron transfer and resulting in fluorescence quenching.

A Cd(II) Luminescent Coordination Grid as a Multiresponsive Fluorescence Sensor for Cr(VI) Oxyanions and Cr(III), Fe(III), and Al(III) in Aqueous Medium

“…Of particular note, the XRPD patterns of the same microcrystalline sample after grinding showed alternations in intensity, and in some peak positions, compared to the simulated XRPD patterns. This is tentatively attributed to the influences of either the variation in preferred orientation of the powdered sample [ 30 ] or the partial crystal structure distortion caused by grinding [ 41 ] or both.…”

“…As a matter of fact, luminescent CP-based chemo/biosensors have been actively used to detect small molecules, explosives, ions, gas, and pH, among others, and several reviews have been devoted to the sensory properties [23][24][25][26][27][28][29]. Recently, we have made advances in fluorescence detection of hazardous chemical contaminants by using luminescent organic-inorganic hybrid materials as sensory platforms [30][31][32][33][34][35][36][37][38][39]. Herein, we report a new Cd(II) based luminescent CP, {[Cd(Br-1,3-bdc)(NI-mbpy-34)(H 2 O)]•2H 2 O} n (1), where NI-mbpy-34 = N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide, Br-1,3-H 2 bdc = 5-bromobenzene-1,3-dicarboxylic acid.…”

Zinc(II)-Based Ring-and-Rod Coordination Layer as an Excitation-Wavelength-dependent Dual-Emissive Chemosensor for Discriminating Fe3+, Cr3+, and Al3+ in Water

“…Designing organic luminophore (or fluorophore) derivatives as linkage struts to link closed-shell metal ions as nodes is a general but effective synthesis strategy to facilitate the fabrication of luminescent CPs. − Based on this strategy, most main-group (s- and p-block) and transition (d-block) metal-based CPs lead to a structureless emission at a single wavelength under single excitation that is originated from ligand-based (ligand-centered, metal-to-ligand, or ligand-to-metal) transitions and usually reveal luminescence quenching or enhancement response to achieve sensing functions. − In comparison, dual-emissive luminescent CP materials under single excitation are usually observed in rare-earth (f-block) metal based CPs, which display columinescence of ligand-centered transitions and characteristic 4f–4f transition of lanthanide­(III) centers, , and have further ratiometric sensing behaviors. − Other than lanthanide based CPs, only few examples of non-f-block CP sensors with two different emission wavelengths have been documented. − Apart from typical dual-emissive luminescent materials, there are also excitation-wavelength-dependent dual- or multi-emissive luminescent materials, which are mainly utilized in color-tunable light-emitting materials, (near) white-light emitting materials, anti-counterfeiting labels, and bioimaging. − Only a few of excitation-wavelength-dependent organic chromophores are used for sensing purpose . However, no excitation-wavelength-dependent dual-emissive luminescent CP sensors are realized up to now.…”

Hetero-interpenetrating porous coordination polymers

“…A great number of interpenetrating networks, which consist of topological and chemical equivalents and thus are called homogeneous interpenetration, with different degrees of interpenetration even as high as 54-fold have been identified. 18,24–27 Moreover, control over (homogeneous) interpenetration has been achieved in several ways. 21,28 In comparison, only a small handful of heterogeneous interpenetrating networks that is interpenetration of two or more networks with different types of topologies and/or chemical compositions are formed rather unexpectedly.…”