Sensitisation of the Near‐Infrared Emission of Nd^III from the Singlet State of Porphyrins Bearing Four 8‐Hydroxyquinolinylamide Chelates

Abstract

The α(4) atropoisomer of a tetraaryl porphyrin and its Pd(II) complex, both bearing four hydroxyquinolinyl chelating units pre-organised on the same face of the porphyrin backbone, bind a Nd(III) centre thus affording either a mononuclear or a heterobinuclear anionic species, respectively. The near-infrared emission of the lanthanide centred at 1064 nm is observed upon excitation of the Soret band at 425 nm. Sensitisation proceeds mainly from the singlet state of the porphyrin.

Pacman Compounds: From Energy Transfer to Cooperative Catalysis

“…Interestingly, the NIR emission intensity for both Nd complexes was only slightly decreased in the presence of O 2 . Furthermore, the lifetime for the phosphorescence of the palladium porphyrin unit was not influenced by the presence of Nd III , indicating that energy transfer proceeds predominantly through the singlet state of the porphyrin moiety and not the triplet state.…”

Contribution of Energy Transfer from the Singlet State to the Sensitization of Eu3+ and Tb3+ Luminescence by Sulfonylamidophosphates

“…[6][7][8] Among thousands of publications on lanthanide complexes,o nly af ew have included evidenceo fadominant singlet (S 1 )p athway. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] Dominant singlet energy transfer has seldom been observed, in the sensitization of lanthanide ions, because intersystem crossing (S 1 !T 1 )i su sually very fast due to not only the rather small S 1 -T 1 energy difference (ca. 5000 cm À1 ), but also to the external heavy-atom effect induced by the lanthanide ion.…”

“…The commonly observed sensitization process for luminescent Eu 3+ and Tb 3+ complexes involves a triplet pathway in which the transfer of the energy absorbed by the ligand to the Ln 3+ ion takes place from the ligand‐centered triplet excited state (T 1 ) . Among thousands of publications on lanthanide complexes, only a few have included evidence of a dominant singlet (S 1 ) pathway . Dominant singlet energy transfer has seldom been observed, in the sensitization of lanthanide ions, because intersystem crossing (S 1 →T 1 ) is usually very fast due to not only the rather small S 1 –T 1 energy difference (ca.…”

Lanthanide–tetrapyrrole complexes: synthesis, redox chemistry, photophysical properties, and photonic applications

“…Although the structural geometry of the over-crowded porphyrin core (as the a 4 -atropisomer) made it impossible for Nd III to be coordinated in the centre, the pendant 8-hydroxyquinoline units could chelate Nd III externally; a heterodinuclear Pd II -Nd III porphyrinate could even be conspicuously formed by a stepwise metalation protocol. 117,118 The authors first synthesized a meso-tetrakis(o-aminophenyl) porphyrin using the Lindsey method. 119 This compound was dissolved in CH 2 Cl 2 along with 4-(N,N-dimethylamino)pyridine (DMAP), 3-[bis(dimethylamino)methyliumyl]-3H-benzotriazol-1-oxide hexafluorophosphate (HBTU, Scheme 1), and 7-carboxy-8-hydroxyquinoline in CH 2 Cl 2 and the mixture was stirred for 4 days under argon and in the dark.…”