Structural Diversity in Six Mixed Ligand Zn(II) Metal–Organic Frameworks Constructed by Rigid and Flexible Dicarboxylates and Different N,N′ Donor Ligands

Abstract

Three different N,N′-donor ligands with Zn(NO 3 ) 2 •6H 2 O and two different dicarboxylates, flexible succinate (suc) and rigid fumarate (fum) afforded six different metal−organic frameworks (MOFs). Among the N,N′-donor ligands, one bent 1,4-bisHere, 3 is a pillared layer structure, whereas 4 has a 5-fold interpenetrated dimondoid network. For both the bent and straight N,N′-donor ligands an imine alike motif is embedded in the structure. When this motif is replaced by a C−C double bond by using the ligand 1,2-bis(4-pyridyl)ethylene (bpee), it produces two MOFs, {[Zn(bpee 6), having a similar structural relation like 3 and 4 respectively, 5 with a pillared layer structure and 6 with a 5-fold interpenetrated diamondoid network. All the compounds have been thoroughly characterized by powder X-ray diffraction (PXRD), elemental analysis, infrared (IR) spectroscopy, UV−vis spectroscopy, and thermogravimetric analyses. Gas/solvent vapor sorption studies have been carried out for compounds 3−6, which have 3D structures. In the case of 3, an interesting reversible crystalline to crystalline transformation was observed which has been thoroughly studied by PXRD analysis, IR spectroscopy, and UV−vis spectroscopy. Solid state emission spectral analysis for all the complexes was performed at room temperature.

Syntheses, Characterization, and Fluorescence Properties of Four Coordination Polymers based on Double Betaine Ligands

“…The excition and emission spectra of compounds 3 and 4 are similar to each other exhibiting emissions at 495 nm ( λ ex = 380 nm) and 492 nm ( λ ex = 375 nm). Since In 3+ and Cd 2+ with d 10 configuration are hard to oxidize or reduce, which exclude the possibility of metal‐to‐ligand charge transfer (MLCT) or ligand‐to‐metal charge transfer (LMCT) induced luminescence , . So the luminescence of compounds 1 – 4 is probably assigned to the intra‐ligand π*→π and/or π*→n transitions, whereas the less than 50 nm wavelength‐shifts are probably caused by the coordination effect according to the literature …”

“…[38,39] So the luminescence of compounds 1-4 is probably assigned to the intra-ligand π*Ǟπ and/or π*Ǟn transitions, whereas the less than 50 nm wavelengthshifts are probably caused by the coordination effect according to the literature. [38][39][40] Z. Anorg. Allg.…”

Assembled synthesis of luminescent mono/double‐layered 2D and 3D Zn (II)‐based coordination polymers tuned by flexible bis (pyridyl)propane‐1,2‐diamines and diverse organic dicarboxylates

“…In contrast to the carboxylates in mixed‐ligands Zn (II)‐based CPs, we mainly focus on the ditopic bis (pyridyl) molecules with specific coordination directivity on the basis of the versatile and changeable spacers . However, in contrast to the most concerned rigid spacers, such as aromatic ring, aliphatic hydrocarbon, aliphatic amine, acylamide in reported works, only a few of them pay attention to the bis (pydidyl) molecules bearing flexible spacer . Therefore, modulating the architectures and properties of Zn (II)‐based CPs through rational design of bis (pyridyl) molecules with flexible spacer would be challenging and thought‐provoking work.…”

Coordination Assemblies of Zn(II) Coordination Polymers: Positional Isomeric Effect and Optical Properties

“…According to the previous studies, the N-donor and O-donor organic compounds are two kinds of the most important ligands, which have been widely used to construct various CPs because of their rich coordination modes, and modifiable backbones [15,16]. Noticeably, rigid rod-type ligands such as bipyridine (bpy), terephthalic acid or their analogues, often employ as linear pillars to construct entangled CPs [17,18]. Besides the rigid ligands, the flexible ligands including flexible N-donor (4-pyridyl)ethane (bpe), (4-pyridyl)propane (bpp), 1,2-bis(4-pyridyl)ethylene (bpee), and O-donor 1,4-phenylenediacetic acid (H 2 pphda) and 1,2-phenylenediacetic acid (H 2 ophda) have different shapes associated with the trans Crystals 2019, 9, or gauche conformation, favoring the formation of interesting topologies [19][20][21][22].…”