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Diarylphosphate as a New Route for Design of Highly Luminescent Ln Complexes.

Authors :: Kalugin AE
Minyaev ME
Puntus LN
Taydakov IV
Varaksina EA
Lyssenko KA
Nifant'ev IE
Roitershtein DM
Source :: Molecules (Basel, Switzerland) [Molecules] 2020 Aug 28; Vol. 25 (17). Date of Electronic Publication: 2020 Aug 28.
Publication Year :: 2020
Abstract: Organophosphate-chloride complexes [{(2,6- <superscript>i</superscript> Pr <subscript>2</subscript> C <subscript>6</subscript> H <subscript>3</subscript> -O) <subscript>2</subscript> POO} <subscript>2</subscript> LnCl(CH <subscript>3</subscript> OH) <subscript>4</subscript> ]·2CH <subscript>3</subscript> OH, Ln = Nd ( 1 ), Eu ( 2 ), Gd ( 3 ), and Tb ( 4 ) have been obtained and structurally characterized. Their reaction with 2,2':6',2″-terpyridine leads to the formation of 1:1 adducts ([{(2,6- <superscript>i</superscript> Pr <subscript>2</subscript> C <subscript>6</subscript> H <subscript>3</subscript> -O) <subscript>2</subscript> POO} <subscript>2</subscript> LnCl(terpy)(H <subscript>2</subscript> O) <subscript>2</subscript> (CH <subscript>3</subscript> OH)], Ln = Eu ( 5 ), Gd ( 6 ), Tb ( 7 ) with exception of Nd, where tris-diisopropylphenylphosphate complex [{(2,6- <superscript>i</superscript> Pr <subscript>2</subscript> C <subscript>6</subscript> H <subscript>3</subscript> -O) <subscript>2</subscript> POO} <subscript>3</subscript> Nd) (terpy)(H <subscript>2</subscript> O)(CH <subscript>3</subscript> OH)] ( 8 ) was obtained due to the ligand metathesis. A bright luminescence observed for the Eu and Tb organophosphate complexes is the first example of an application of organophosphate ligands for 4f-ions luminescence sensitization. Photophysical properties of all complexes were analyzed by optical spectroscopy and an energy transfer scheme was discussed. A combination of two types of ligands into the coordination sphere (phosphate and phenanthroline) allows designing the Eu surrounding with very high intrinsic quantum yield QEuEu (0.92) and highly luminescent Ln complexes for both visible and near-infrared (NIR) regions.