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Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands

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ABSTRACT

1234123412,4314: Four lead(II) coordination polymers were isolated under hydro(solvo)thermal conditions. The applied synthetic methodology takes advantage of the coordination behaviour of a new bifunctional organoarsonate ligand, 4-(1, 2, 4-triazol-4-yl)phenylarsonic acid (H2TPAA) and involves the variation of lead(II) reactants, metal/ligand mole ratios, and solvents. The constitutional composition of the four lead(II) coordination polymers can be formulated as [Pb2(TPAA)(HTPAA)(NO3)]·6H2O (), [Pb2(TPAA)(HTPAA)2]·DMF·0.5H2O (DMF = N, N-Dimethylformamide) (), [Pb2Cl2(TPAA)H2O] (), and [Pb3Cl(TPAA)(HTPAA)2H2O]Cl (). The compounds were characterized by single-crystal and powder x-ray diffraction techniques, thermogravimetric analyses, infra-red spectroscopy, and elemental analyses. Single-crystal x-ray diffraction reveals that and represent two-dimensional (2D) layered structures whilst and form three-dimensional (3D) frameworks. The structures of , and contain one-dimensional (1D) {PbII/AsO3} substructures, while is composed of 2D {PbII/AsO3} arrays. Besides their interesting topologies, – all exhibit photoluminescence properties in the solid state at room temperature.

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Emission spectra for 1–4 in the solid state at room temperature (excitation bands for 1–4 are 380 nm, 380 nm, 380 nm and 370 nm, respectively).
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Figure 5: Emission spectra for 1–4 in the solid state at room temperature (excitation bands for 1–4 are 380 nm, 380 nm, 380 nm and 370 nm, respectively).

Mentions: Hybrid coordination compounds containing Pb(II) ions may have interesting photochemical and photophysical properties [61–67, 86]. However, in comparison to many transition metal or lanthanide systems, the photoluminescence properties of lead(II)-organic frameworks are less explored. To further characterize 1–4, their photoluminescence properties were investigated in the solid state at room temperature. As illustrated in figure 5, emission bands at 461 and 486 nm (λex = 380 nm) for 1, 438 nm (λex = 380 nm) for 2, 458, 478, and 531 nm (λex = 380 nm) for 3 and 458 and 550 nm (λex = 370 nm) for 4 are observed. For H2TPAA, an emission band maximum centered at 456 nm is apparent upon photoexcitation at 373 nm (SI, figure S8). The emission bands at 461 nm of 1, 438 nm of 2, 458 nm of 3, and 458 nm of 4 may be due to the π → π∗ transition, as an approximate emission peak (456 nm) also appears in the spectra of the H2TPAA ligand. The emission bands at 486 nm of 1 and 478 nm of 3 can be attributed to ligand-to-metal charge transfer (LMCT) transitions involving delocalized π bonds of the aromatic arsonate groups and the p orbitals of Pb(II) centers. The low-energy emissions with large stokes shift, characteristic for the bands at 531 nm for 3 and 550 nm for 4, can be assigned to metal-centered transitions involving s and p orbitals, as proposed by Vogler [87, 88].


Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands
Emission spectra for 1–4 in the solid state at room temperature (excitation bands for 1–4 are 380 nm, 380 nm, 380 nm and 370 nm, respectively).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036471&req=5

Figure 5: Emission spectra for 1–4 in the solid state at room temperature (excitation bands for 1–4 are 380 nm, 380 nm, 380 nm and 370 nm, respectively).
Mentions: Hybrid coordination compounds containing Pb(II) ions may have interesting photochemical and photophysical properties [61–67, 86]. However, in comparison to many transition metal or lanthanide systems, the photoluminescence properties of lead(II)-organic frameworks are less explored. To further characterize 1–4, their photoluminescence properties were investigated in the solid state at room temperature. As illustrated in figure 5, emission bands at 461 and 486 nm (λex = 380 nm) for 1, 438 nm (λex = 380 nm) for 2, 458, 478, and 531 nm (λex = 380 nm) for 3 and 458 and 550 nm (λex = 370 nm) for 4 are observed. For H2TPAA, an emission band maximum centered at 456 nm is apparent upon photoexcitation at 373 nm (SI, figure S8). The emission bands at 461 nm of 1, 438 nm of 2, 458 nm of 3, and 458 nm of 4 may be due to the π → π∗ transition, as an approximate emission peak (456 nm) also appears in the spectra of the H2TPAA ligand. The emission bands at 486 nm of 1 and 478 nm of 3 can be attributed to ligand-to-metal charge transfer (LMCT) transitions involving delocalized π bonds of the aromatic arsonate groups and the p orbitals of Pb(II) centers. The low-energy emissions with large stokes shift, characteristic for the bands at 531 nm for 3 and 550 nm for 4, can be assigned to metal-centered transitions involving s and p orbitals, as proposed by Vogler [87, 88].

View Article: PubMed Central - PubMed

ABSTRACT

1234123412,4314: Four lead(II) coordination polymers were isolated under hydro(solvo)thermal conditions. The applied synthetic methodology takes advantage of the coordination behaviour of a new bifunctional organoarsonate ligand, 4-(1, 2, 4-triazol-4-yl)phenylarsonic acid (H2TPAA) and involves the variation of lead(II) reactants, metal/ligand mole ratios, and solvents. The constitutional composition of the four lead(II) coordination polymers can be formulated as [Pb2(TPAA)(HTPAA)(NO3)]·6H2O (), [Pb2(TPAA)(HTPAA)2]·DMF·0.5H2O (DMF = N, N-Dimethylformamide) (), [Pb2Cl2(TPAA)H2O] (), and [Pb3Cl(TPAA)(HTPAA)2H2O]Cl (). The compounds were characterized by single-crystal and powder x-ray diffraction techniques, thermogravimetric analyses, infra-red spectroscopy, and elemental analyses. Single-crystal x-ray diffraction reveals that and represent two-dimensional (2D) layered structures whilst and form three-dimensional (3D) frameworks. The structures of , and contain one-dimensional (1D) {PbII/AsO3} substructures, while is composed of 2D {PbII/AsO3} arrays. Besides their interesting topologies, – all exhibit photoluminescence properties in the solid state at room temperature.

No MeSH data available.