Metal–Organic Frameworks for Separations

Luminescent Functional Metal–Organic Frameworks

Metal–organic frameworks (MOFs) display a wide range of luminescent behaviors resulting from the multifaceted nature of their structure. In this critical review we discuss the origins of MOF luminosity, which include the linker, the coordinated metal ions, antenna effects, excimer and exciplex formation, and guest molecules. The literature describing these effects is comprehensively surveyed, including a categorization of each report according to the type of luminescence observed. Finally, we discuss potential applications of luminescent MOFs. This review will be of interest to researchers and synthetic chemists attempting to design luminescent MOFs, and those engaged in the extension of MOFs to applications such as chemical, biological, and radiation detection, medical imaging, and electro-optical devices (141 references).

Luminescent Metal–Organic Frameworks

/pdf/metal-organic-frameworks-and-self-assembled-supramolecular-2xs948xxr9.pdf

Metal–Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and Contrasting the Design, Synthesis, and Functionality of Metal–Organic Materials

Polycatenation, polythreading and polyknotting in coordination network chemistry

Six noninterpenetrating or- ganic ± inorganic hybridized coordina- tion complexes, (Mn(3)2(H2O)2)- (ClO4)2 ¥2 H2 O( 5), (Mn(3)2(H2O)2)- (NO3)2 (6), (Mn(3)2(N3)2 )¥2 H2 O( 7), (Cu(3)2(H2O)2)(ClO4)2 (8), (Mn(4)2- (H2O)(SO4)) ¥ CH3OH ¥ 5 H2 O( 9) and (Mn(4)2)(ClO4)2 (10) were obtained through self-assembly of novel tripodal ligands, 1,3,5-tris(1-imidazolyl)benzene (3) and 1,3-bis(1-imidazolyl)-5-(imida- zol-1-ylmethyl)benzene (4) with the cor- responding metal salts, respectively. Their structures were determined by X-ray crystallography. The results of structural analysis of complexes 5, 6, 7, and 8 with rigid ligand 3 indicate that their structures are mainly dependant on the nature of the organic ligand and geometric need of the metal ions, but not influenced greatly by the anions and metal ions. While in complexes 9 and 10, which contain the flexible ligand 4, the counteranion plays an important role in the formation of the frameworks. En- tirely different structures of complexes 5 and 10 indicate that the organic ligands greatly affect the structures of assem- blies. Furthermore, in complexes 5 and 6, the counteranions located between the cationic layers can be exchanged by other anions. Reversible anion exchang- es between complexes 5 and 6 without destruction of the frameworks demon- strate that 5 and 6 can act as cationic layered materials for anion exchange, as determined by IR spectroscopy, elemen- tal analyses, and X-ray powder diffrac- tion.

Reversible Anion Exchanges between the Layered Organic–Inorganic Hybridized Architectures: Syntheses and Structures of Manganese(II) and Copper(II) Complexes Containing Novel Tripodal Ligands

A series of Bi3+,Eu3+-doped Sr2Y8(SiO4)6O2 (SYSO) phosphors were synthesized by the Pechini-type sol–gel route. XRD patterns, Rietveld refinement, FT-IR spectra, photoluminescence spectra (PL), fluorescence decay time, and quantum yields (QYs) were utilized to characterize the as-prepared samples. Intense blue-green emission due to the 3P1 → 1S0 transition of Bi3+ ions is produced under UV excitation in Bi3+ singly doped SYSO samples. Spectral analysis illustrates that two kinds of Bi3+ ions are generated by occupying the two kinds of sites (4f and 6h) available for Y in SYSO, denoted as Bi3+(1) and Bi3+(2), corresponding to the two main emission bands at around 413 and 493 nm, respectively. A wide spectral overlap between Bi3+ emission and Eu3+ excitation spectra results in the energy transfer from Bi3+ to Eu3+. This has been demonstrated via the excitation spectra monitored at Bi3+ and Eu3+ emission bands, and the PL emission spectra and decay time of Bi3+ in SYSO:Bi3+,Eu3+ phosphors. The energy transfer mechanism is determined to be dipole–quadrupole interaction. The critical distance of energy transfer from Bi3+ to Eu3+ ions is calculated to be 12.78 A based on the concentration quenching method, which is in good agreement with that of the spectral overlap route (10.03–13.37 A). Moreover, the QYs, CIE chromaticity and thermal quenching properties have also been investigated. White emission color can be realized with the CIE coordinates (0.325, 0.311) and QY 52% for SYSO:0.08Bi3+,0.48Eu3+. The above results suggest that SYSO:Bi3+,Eu3+ can be a potential single-component white-emitting phosphor for UV w-LEDs.

Sr2Y8(SiO4)6O2:Bi3+/Eu3+: a single-component white-emitting phosphor via energy transfer for UV w-LEDs

Seven new Zn(II) metal−organic frameworks [Zn(tib)2(H2O)](ClO4)2 (1), [Zn4(tib)2(PBDA)3(OH)2]·4H2O (2), [Zn(tib)(HPBDA)]ClO4 (3), [Zn2(tib)(PBDA)Cl2]·2H2O (4), [Zn4(tib)2(PBDA)3Cl2] (5), [Zn2(tib)2(PBDA)](NO3)2·2H2O (6), and [Zn2(tib)(PBDA)I2]·2H2O (7) [tib = 1,3,5-tris(1-imidazolyl)benzene, H2PBDA = p-benzenedicarboxylic acid] have been prepared and characterized by elemental, IR, thermogravimetric and X-ray diffraction analyses. Complexes 1 and 4 are two-dimensional (2D) networks with different topologies, which are further linked together to three-dimensional (3D) frameworks by hydrogen bonds. For 3, partial deprotonated HPBDA− is terminally coordinating to Zn(II) to form a 2D network. Complexes 2, 5, and 7 are 2-fold interpenetrated 3D frameworks, while 6 has a self-penetrating 3D structure. The influences of reaction temperature and counteranion on the structures of the complexes are discussed. The photoluminescence and nonlinear optical properties are investigated.

Interpenetrating and Self-Penetrating Zinc(II) Complexes with Rigid Tripodal Imidazole-Containing Ligand and Benzenedicarboxylate

Three five-component archi- tectures, compounds 3, 4, and 5 were obtained by self-assembly of tripodal 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-tri- methylbenzene (6) and 1,3,5-tris(benz- imidazol-2-ylmethyl)benzene (7) li- gands with silver(i) salts. The structures of these novel complexes have been determined by X-ray crystallography. The results of structural analysis indicate that these frameworks have same M3L2 components, but different structures. Compounds 3 and 4 are both M3L2 type cage-like complexes, while the 5 is an open trinuclear complex. The complex 3 is a cylindrical cage with simultaneous inclusion of a perchlorate anion inside of the cage as a guest molecule. Such guests can be exchanged for other anions through the open edge of the cage as evidenced by crystal structure of 4 .T he results demonstrate that the molecular M3L2 type cage can act as a host for anions and provide a nice example of supramolecular architectures with inter- esting properties and possible applica- tions.

Self-assembly of frameworks with specific topologies: construction and anion exchange properties of M3L2 architectures by tripodal ligands and silver(I) salts.

The influence of Mg2+-Si4+/Ge4+ incorporation into Ce3+-doped Y3Al5O12 garnet phosphors on the crystal structure and luminescence properties is described in this work. X-ray diffraction with Rietveld refinements, photoluminescence spectra, absolute quantum yield, thermal quenching behavior, and lifetimes were utilized to characterize samples. The introduction of Mg2+-Si4+/Ge4+ leads to an obvious red shift of emission wavelength under the excitation of blue light, especially for the series of Mg2+-Si4+ substitutions, which is suited for white light-emitting diodes (LEDs) with low color temperatures and good color rendering using only a single phosphor. More interestingly, an additional emission band locating at high-energy was observed with ultraviolet excitation, which is different than previous literature. Under the excitation of ultraviolet, the emission color for the Mg2+-Si4+ substitutions can be tuned from yellow-green to blue, which is expected to obtain single-phased phosphors with white emission excited with UV-LED chip. The usual Ce3+ emission band at low energy has stronger quenching at high temperatures. The mechanisms for the observed phenomena are discussed.

Jian Fan

Papers

Reversible Anion Exchanges between the Layered Organic–Inorganic Hybridized Architectures: Syntheses and Structures of Manganese(II) and Copper(II) Complexes Containing Novel Tripodal Ligands

Sr2Y8(SiO4)6O2:Bi3+/Eu3+: a single-component white-emitting phosphor via energy transfer for UV w-LEDs

Interpenetrating and Self-Penetrating Zinc(II) Complexes with Rigid Tripodal Imidazole-Containing Ligand and Benzenedicarboxylate

Self-assembly of frameworks with specific topologies: construction and anion exchange properties of M3L2 architectures by tripodal ligands and silver(I) salts.

A double substitution of Mg2+-Si4+/Ge4+ for Al(1)(3+)-Al(2)3+ in Ce3+-doped garnet phosphor for white LEDs.