Effect of the flexible chain length of a dimetal subunit on the formation of 1D coordination polymers to molecular rectangles

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Utilizing a cautious design of luminescent MOFs of non-d 10 divalent transition metals based on two factors (metal nodes in an octahedral geometry to minimize nonradiative energy dissipation and tailored organic chromophores), this work reports {[Ni 2 (oxdz) 2 (tpbn)]} n (1), {[Ni 2 (oxdz) 2 (tphn)]} n (2), and {[Ni 2 (oxdz) 2 (tpon)]} n (3), synthesized at room temperature, varying the spacer length of tpbn/tphn/tpon (four, six, and eight CH 2 groups, respectively). This subtle change in 1−3 is correlated to their hydrophobicity and polarizing power via water vapor sorption and selective and sensitive detection of aldehydes at the ppb level, respectively. A decrease in water vapor uptake (14.8, 8.95, and 3.19 mmol g −1 for 1−3, respectively) is observed with an increase in their hydrophobicity. On the other hand, the solution phase detection limits of acetaldehyde and benzaldehyde (2.42 and 6.71 ppb for 1, 2.77 and 4.08 ppb for 2, and 10.35 and 10.4 ppb for 3, respectively) show a similar trend for their polarizing power. The best performance of 1 is expanded to the vapor-phase detection of acetaldehyde (297% luminescence enhancement) under different pH conditions. The second mode of detection of acetaldehyde via the metal-centered electrochemical behavior of 1 provides detection limits of 38.2 and 71.5 ppb at pH 7 and 13, respectively.

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Strategic Design of Non-d¹⁰ Luminescent Metal–Organic Frameworks as Dual-Mode Ultrafast and Selective Sensing Platforms for Aldehydes at the ppb Level

Bhambri,

Mandal

2024

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“…Therefore, it is a challenging task to make MOFs with flexible N-donor linkers. Among the flexible linkers, the representative examples with two, four, and six N-donor atoms (shown in Figure ) have been systematically studied for the effect of denticity and flexibility on the structural features and dimensionalities of the architectures. ,,,,,− While the examples of linkers with two N-donor atoms have been reported by many researchers including us, − the linkers with six N-donor atoms have been utilized exclusively by our group. ,,,,− The tetradentate ligand, tetrakis(4-pyridyloxymethylene)methane (4-tpom), with four pyridyl groups around the carbon core with a second hetero atom, oxygen, is different from the other two sets.…”

Section: Introductionmentioning

confidence: 99%

“…One of the salient features of 4-tpom is that it can adopt different conformations in the frameworks depending upon the coordination preference of the metal center or the coordination mode and alignment of the dicarboxylate. This neutral ligand can undergo such conformational changes by varying the angles between the central carbon atom of the pentaerythrityl core and the nitrogen atom of the pyridyl group as well as the C core –CH 2 –O–C torsion angles. , On the other hand, for combining 4-tpom with various dicarboxylates to develop diverse 3D MOFs, we have exploited the exocyclic angle between the carboxylate groups from 180° to 120° as shown in Figure . ,, Recently, we reported several examples of 2D and 3D MOFs consisting of linkers with six N-donor atoms along with the bent dicarboxylate, oxdz 2– , which has an exo angle of 144° between the carboxylate groups attached to the rigid phenyl group extension on the oxadiazole moiety. , Hence, we decided to explore the chemistry of 4-tpom in combination with oxdz 2– and a divalent metal ion such as Zn(II) or Cd(II) for the fact that the exocyclic angle of oxdz 2– (144°) fills the gap in the series of rigid carboxylates, such as 1,3-bdc 2– (120°), 3,7-dbtdc 2– (163°), and 1,4-ndc 2– (180°). ,,− …”

Section: Introductionmentioning

confidence: 99%

A Multivariate 2D Metal–Organic Framework with Open Metal Sites for Catalytic CO₂ Cycloaddition and Cyanosilylation Reactions

Chanda,

Mandal

2024

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This work reports the synthesis of a dual functional 2D framework, {[Zn 2 (4-tpom) 2 (oxdz) 2 ]•4H 2 O} n (1), at room temperature, where a bent dicarboxylate, oxdz 2− (4,4′-(1,3,4-oxadiazole-2,5-diyl)dibenzoate), and a neutral flexible N-donor linker, 4-tpom (tetrakis(4pyridyloxymethylene)methane), are utilized. Its single-crystal X-ray analysis indicated a 2-fold interpenetrated 2D framework having tetracoordinated Zn(II) centers and dangling pyridyl groups. Its further characterization was carried out with elemental microanalysis, FTIR spectroscopy, TG analysis, and powder X-ray diffraction. The tetracoordinated Zn(II) centers as active Lewis acidic sites and the N atoms of 4-tpom as Lewis basic sites in 1 are explored for its functioning as a heterogeneous catalyst in two important reactions, (i) cycloaddition of CO 2 with various epoxides and (ii) cyanosilylation reaction under solvent-free conditions. We could successfully show the cycloaddition of styrene oxide with CO 2 (99% conversion) under balloon pressure with low catalyst (0.2−0.3 mol %) and cocatalyst (0.5−0.75 mol %) loadings, which is otherwise difficult to achieve. It was observed that all the substrates (aromatic and aliphatic), irrespective of their sizes, showed conversion percentage >99%. In the cyanosilylation reaction, a conversion of 96% was obtained with 1.5 mol % of 1 at room temperature for 12 h. This framework emerged as an excellent recyclable catalyst for both the reactions.

“…Therefore, in this work, we considered a simple, commercially available bent dicarboxylate, 2,5-furan dicarboxylate (fdc 2– ), which has an exo angle of 141°. Although fdc 2– has been widely explored to synthesize multidimensional MOFs, − no such fused ring system is observed for a combination with any neutral linker.…”

Section: Introductionmentioning

confidence: 99%

Two Metal–Organic Frameworks with a Fused Cis-Decalin Conformation for Multimedia Iodine Capture

Chanda,

Mandal

2024

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The extensive growth of nuclear power plants has a severe detrimental effect on human health and the surroundings due to the uncontrolled and unfiltered release of radioactive wastes into the environment. One such radioactive waste is 129 I which has a fatal effect when released into the air or water bodies. Hence, molecular and ionic iodine capture from multimedia has become an important area of interest in the recent past. This work is aimed at introducing two 2D metal−organic frameworks with a fused cis- 2), synthesized at room temperature utilizing a combination of M(OAc) 2 •2H 2 O (M: Zn/ Cd), a neutral flexible ligand, tpbn, and a simple commercially available furan dicarboxylate, fdc 2− , for the target application. The polarizing nature of the furan moieties and the oxygen rich pores in 1 and 2 facilitate the easy capture of molecular iodine from both the vapor phase and aqueous media with high uptake values. Furthermore, their efficiency was tested for the practical application under real-world conditions using river and seawater. In addition to confirming their recyclability with the retention of structural integrity, the interaction between 1 and 2 with iodine has also been established with experimental and theoretical calculations.