Coordination polymers based on a glycine-derivative ligand

• Published in: CrystEngComm 2014-01, Vol.16 (35), p.8119-8137
• Main Authors: Vilela, Sérgio M. F., Ananias, Duarte, Silva, Patrícia, Nolasco, Mariela, Carlos, Luís D., de Zea Bermudez, Verónica, Rocha, João, Tomé, João P. C., Almeida Paz, Filipe A.
• Format: Article
• Language: English
• Subjects: Chlorides; Coordination polymers; Diffraction; Emission; Excitation spectra; Photoluminescence; Single crystals; X-rays
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/C4CE00465E

The combination of the glycine-derivative supramolecular salt 4,6-bis(carboxymethylamino)-2-oxo-2,3-dihydro-1,3,5-triazin-1-ium chloride (H 2 bodt·HCl) and lanthanide( iii ) chloride hydrates under hydrothermal conditions (120 °C, 48 h) led to the formation of a family of isotypical materials formulated as [Ln(bodt)(Hbodt)] [where Ln 3+ = La 3+ ( 1 ), (La 0.95 Eu 0.05 ) 3+ ( 2 ) and (La 0.95 Tb 0.05 ) 3+ ( 3 )]. The synthesis of the novel precursor H 2 bodt·HCl is detailed. The structures of H 2 bodt·HCl and its intermediate compound were unveiled by single-crystal X-ray diffraction and characterized by standard liquid-state techniques. The crystallographic details of compound 1 were unveiled in the monoclinic P 2/ c space group by using single-crystal X-ray diffraction, with the crystal structure of 1 comprising a one-dimensional ∞ 1 [La(bodt)(Hbodt)] coordination polymer. All polymeric materials were fully characterized by FT-IR, electron microscopy (SEM and EDS), powder X-ray diffraction, and elemental and thermogravimetric analyses. The photoluminescent properties of 1 and of the mixed-lanthanide materials 2 and 3 were investigated at ambient and low temperatures. An excited-state intermolecular proton transfer (ESPT) process, induced by intermolecular hydrogen-bonding interactions, is proposed to account for the observed anomalous emission and excitation spectra of 1 . Aiming at providing an in-depth understanding of the emission (fluorescence and phosphorescence) properties of the ligand, time-dependent density functional theory (TD-DFT) calculations were also performed.