Photoluminescence coordination polymers

Zinc carboxylate interactions have been exploited as part of a fluorescent molecular sensor for uronic acids. The sensors feature two interactions coordination of the carboxylate to the zinc and a boronic acid diol interaction.389 Photoluminescent coordination polymers from hydrothermal syntheses containing Zn40 or Zn4(OH)2 cores with isophthalate or fumarate and 4,4 -bipyridine form two- and three-dimensional structures. Single X-ray diffraction of both dicarboxylates identified the network structure.373... 

Polymeric structures based on networks of homoleptic eight-coordinate La(III) centers linked through 2,2 -bipyridine-A/ 77 -dioxide have been prepared, for example, by the reaction of La(CF3S03)3 and 2,2 - and 4,4 -bipyridine-A(A/ -dioxide in methanol at 20 °C [122]. The reaction of FeCl2, 1,10-phenanthroline and benzene-1,2,4,5-tetracarboxylate in water at 160 °C in a Teflon reactor produces a two-dimensional polymeric structure of [Fe(phenanthroline)-(benzenecarboxylate)] [123]. Multi-dimensional metalorganic coordination polymers with metal-aromatic interaction which exhibit strong photoluminescent behavior have been prepared by different Ag(I)-naphthalene-carboxylates with hexamethylenetetramine in CH2CI2 [124]. 

Liu JC, Cao J, Deng WT, Chen BH. Synthesis, crystal structure, photoluminescent, and electrochemical properties of a novel 2-D silver(I) coordination polymer with lH-l,2,4-triazole-1 -methylene-1 H-benzimidazole-1 -acetic acid. J Chem Crystallogr 2011 41(6) 806-10. 

Fu S, Zhang GX, Han ZB. Synthesis, structure, and photoluminescence of a 3D zinc(II) coordination polymer with tris(2-carboxyethyl)-isocyanurate and 1,2,4-triazole ligands. Z Anorg Allg Chem 2011 637(14-15) 2153-6. 

Yang J, Yue Q, Li G-D et al (2006) Structures, photoluminescence, up-conversion, and magnetism of 2d and 3d rare-earth coordination polymers with multicarboxylate linkages. Inorg Chem 45 2857-2865... 

The study of Eu and Tb MOF coordination polymers showed that they are characterized by strong photoluminescence peaks at 580-695 nm for Eu and 490-620nm for Tb due to f -f transitions [234], The luminescent properties of Tb-, Yb, and Eu-MOFs were also reported in Ref. [235], and they were shown to be sensitive to the molecules present in the MOF cavities. 

Chen LF, Li ZJ, Qin YY, Cheng J-K, Yao Y-G. Syntheses, crystal structures and photoluminescence of two new pyrazinecarboxylate-based cadmium(II) coordination polymers. J Mol Struct 2008 892 278-82. 

Recently, a very interesting example of solvatochromism was reported by Fujiki and co-workers.206 Poly(methyl-3,3,3-trifluoropropylsilylene), 87, synthesized via Wurtz coupling, showed solvatochromism as a result of weak, non-covalent intramolecular Si- -F-G interactions which rendered the conformation of the polysilane uniquely controllable by solvent choice and molecular weight. UV, shown in Figure 18, photoluminescence, NMR, and viscosity studies on the polymer indicated a 73 helical rod-like conformation at room temperature in non-coordinating solvents (e.g., toluene and decane), since the intramolecular interaction resulted in constraining the chain in a rigid helix. 

As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift. The charge-carrier mobility of different EHO-OPPE-Pt samples was determined by TOE measurements as described above for the neat EHO-OPPE. The shape of the photocurrent transients of all EHO-OPPE-Pt samples was similar to those shown in Figs. 6 and 7 for the neat EHO-OPPE. This indicates that these organometallic conjugated polymers networks are also characterized... 

Luminescent coordination compounds continue to attract considerable attention. Zink recently reported a new mixed-ligand copper(I) polymer that shows interesting photoluminescence (232). The complex [CuCl(L44)Ph3P] consists of a one-dimensional chain lattice of metal ions bridged by both Cl" ions and pyrazine molecules. The compound shows conductivity of less than 10-8 S cm 1. The absorption spectrum of the complex shows a band at 495 nm, which could be interpreted as the promotion of an electron from the valence band to the conduction band. On the basis of resonance Raman spectra, the lowest excited state in the polymer is assigned to the Cu(I)-to-pyrazine metal-to-ligand charge-transfer excited state. 

The photoluminescence efficiencies of the synthesized m,/7-phenylenevinylenes reached pretty high levels (up to 52%), but there are still some improvements to be made in connection with solubility. It will be necessary to use only substituted comonomers in order to achieve higher molecular weights and an increased processability of the polymers. As ADMET polymerizations of ortho-alkoxy substituted divinylbenzenes are very slow due to coordination of the oxygen at the molybdenum atom of the catalyst and the substituent should be alkyl in o- or m-positions. 

The reactions of PBpy with [Ru(bpy)2Cl2] in water at reflux gives a light-orange polymer complex (78) in which 1.3-1.4moI% of the bpy units of PBpy coordinate to Ru [158]. The photoluminescence spectrum of the methanol-extractable fraction produces a strong emission band at 519 nm, which is compared... 

Another interesting example of Ag(I)-backbone organometallic polymers are those based on diallylmelamine and poly-carboxylates. Silver-vinyl bonding represents a versatile synthon for the construction of polymeric metallosupramolecular architectures. The particular structural motifs result from the introduction of different auxiliary polycarboxylates into the silver/diallylmelamine system and the diverse coordination modes and conformations of diallylmelamine (Fig. 29.3) [108]. Remarkably, apparent silver-vinyl interactions with a ri mode were commonly observed in the solid-state structures of these complexes (Ag-C = 2.311(4)-2.467(5)A). In addition, they display solid-state photoluminescence and moderate thermal stabilities at room temperature. 

---