Near-infrared luminescent Sn(IV) complexes of N-confused tetraphenylporphyrin: Effect of axial anion coordination

Abstract

Novel tin(IV) halo complexes of an N-confused tetraphenylporphyrin with different axial ligands have been synthesized and characterized by various spectroscopic methods including X-ray crystallographic analysis. The molecular structures of the dichloro and dibromo derivatives possess perfect octahedral geometries, which are nearly comparable to the corresponding regular porphyrin complexes. In contrast, the iodide/triiodide complex obtained by a same reaction manner, demonstrated that the tin(IV) cation is slightly displaced towards axially coordinated iodide anion, giving rise to the different electronic structure due to the tautomeric form of N-confused porphyrin ligand. These structural differences reflected to the distinct photophysical and electrochemical properties. The Sn(IV) complexes are near IR luminescent, however the unsymmetrical axial coordination of iodide and triiodide anions in the tin(IV) N-confused porphyrin complex allows, in particular, the longer emission lifetimes and a smaller singlet-triplet energy gap, which were investigated by steady-state and time-resolved spectroscopies as well as theoretical calculations.

Photodynamic Antitumor and Antimicrobial Activities of Free‐Base Tetra(4‐methylthiolphenyl)chlorin and Its Tin(IV) Complex

“…The fluorescence emission maximum for 3‐Sn lies at 656 nm. The fluorescence quantum yield (Φ F ) values of the Sn(IV) complex are lower than that of 3 due to the heavy atom effect imparted by the Sn(IV) ion [17] . Significant fluorescence quenching is observed for 3‐Sn .…”

“…The fluorescence quantum yield (Φ F ) values of the Sn(IV) complex are lower than that of 3 due to the heavy atom effect imparted by the Sn(IV) ion. [17] Significant fluorescence quenching is observed for 3-Sn. To acquire timeresolved fluorescence data, time-correlated single-photon counting (TCSPC) was used to determine fluorescence lifetime (τ F ) values.…”

Definition of the tetrel bond

“…– the tetrel atom in the cations CH 3 SiH 2 + , 97 TtH 3 + (Tt = C, Si, Ge), 98 C 6 H 15 O 2 SSi + , 99 C 16 H 34 ClN 4 O 2 Si + , 100 C 9 H 21 GeN 3 2+ , 101 C 9 H 31 O 3 Sn 3 + , 102 C 24 H 27 GeN 2 O 3 + , 103 C 44 H 28 IN 4 Sn + , 104 C 6 H 18 PSn + , 105 C 9 H 18 NSn + , 106 C 6 H 19 OSn 2 + , 107 H 6 O 3 Pb 2+ , 108 C 12 H 24 O 4 PbSe 2 2+ , 109 C 24 H 20 N 4 O 2 Pb 2+ , 110 and the carbon atom in the methyl group in the derivatives of ammonium (for example, CH 3 NH 3 + and [C n H 2 n +1 NH 3 ] + ( n = 2, 3, …18)), 49 as well as in carbocation derivatives ( e.g. , CH 3 + , C(CH 3 ) 3 + , etc.…”

Creation from Confusion and Fusion in the Porphyrin World─The Last Three Decades of N-Confused Porphyrinoid Chemistry

“…There are two types of anion-binding mode in NCP tin­(IV) complexes (Scheme ). , In the case of Sn IV (NCP)­Cl 2 632 , anion was recognized at the peripheral NH moiety to give 633 as in the case of free-base NCP. It showed moderate association constants with moderate changes in the photophysical properties.…”