Selective one-step synthesis of triple-decker (porphyrinato)(phthalocyaninato) early lanthanides: the balance of concurrent processes

Tridentate Nitrogen Ligand as a Tool for the Construction of Well-Defined Rare Earth Trichloride Complexes

LnCl3(THF)3 (Ln = Y, La ÷ Nd, Sm ÷ Lu) readily react with the tridentate 1,3,5-trimethyl-1,3,5-triazacyclohexane (Me3tach) ligand to form mono- or binuclear lanthanide trichloride complexes, depending on the stoichiometry of the reaction and the ionic radius of the metal: mononuclear pseudosandwich [LnCl3(Me3tach)2], (Ln = Y, La ÷ Ho) or binuclear complexes [Ln2Cl6(Me3tach)3], or [LnCl3(Me3tach)(THF)]2 (Ln = Sm, Tb). Detailed analysis of the NMR data of [LnCl3(Me3tach)2] complexes with paramagnetic lanthanide ions showed that their structures remained unchanged in the toluene solution. A series of isomorphous complexes [LnCl3(Me3tach)(Py)2] (Ln = La, Sm, Tb, Er, Lu; Py = pyridine) have been obtained by the recrystallization of either mononuclear or binuclear complexes from pyridine. Complexes of terbium and europium ions with the Me3tach ligand exhibit relatively high quantum yields of metal-centered luminescence (0.39 and 0.32, respectively).

Rare-earth based tetrapyrrolic sandwiches: chemistry, materials and applications

This review summarises advances in chemistry of tetrapyrrole sandwiches with rare earth elements and highlights the current state of their use in single-molecule magnetism, organic field-effect transistors, conducting materials and nonlinear optics.

Organometallic complexes of neodymium: an overview of synthetic methodologies based on coordinating elements

Organometallic complexes of neodymium have unique coordinating ability to form both micro and macromolecules as well as metal-based polymers. These complexes have been reported in different fields and play a tremendous role in luminescence, catalytic, biological and magnetic applications. So, the current study will comprise all possible routes for the synthesis of organometallic complexes of neodymium. Neodymium complexes have been synthesized of single, double, triple and tetra linkages with H, C, N, O as well as S, B, and X. The detailed synthetic routes have been classified into four categories but in brief, neodymium forms complexes by reacting metal chloride, nitrate or oxide (hydrated or dehydrated) as precursor along with appropriate ligand. Most applied solvents for neodymium complexes were Toluene and THF. These complexes required a range of temperature based on the nature of complexes as well as linkages. The authors have surveyed the research work published through 2011–2020 and provide a comprehensive overview to understand the synthetic routes of organometallic complexes of neodymium.

Functionalized heterocycle-appended porphyrins: catalysis matters

The scope and limitations of the condensation of labile 2,3-diaminoporphyrin derivatives with aromatic aldehydes to provide functionalized imidazole- and pyrazine-appended porphyrins were investigated in detail. The presence of an acidic catalyst in the reaction was found to be a tool that allows the reaction path to be switched. The influence of the electronic origin of the substituents in the carbonyl components of the condensation on the yields and selectivity of the reaction was revealed. Metal-promoted cross-coupling transformations were found to be convenient for the further targeted construction of functional derivatives based on the prepared bromo-substituted pyrazinoporphyrins. Overall, these strategies provide a versatile technique for the elaboration of a variety of functionalized heterocycle-appended porphyrins for further application in the development of hybrid materials.

Straightforward and Controlled Synthesis of Porphyrin-Phthalocyanine-Porphyrin Heteroleptic Triple-Decker Assemblies

A versatile and straightforward protocol is disclosed for controlled synthesis of complex lanthanide-bridged heteroleptic porphyrin-phthalocyanine triple-decker assemblies. Two porphyrins, linked by a flexible spacer chain of intermediate length, sequentially capture lanthanide ions and a phthalocyanine to efficiently form the triple-decker complex. The bridge directs assembly, but also controls the mobility of the central macrocycle and further imparts a fully eclipsed arrangement of all three rings.

Impressive near-infrared brightness and singlet oxygen generation from strategic lanthanide-porphyrin double-decker complexes in aqueous solution

Although lanthanide double-decker complexes with hetero-macrocyclic ligands as functional luminescent and magnetic materials have promising properties, their inferior water solubility has negated their biomedical applications. Herein, four water-soluble homoleptic lanthanide (Ln = Gd, Er, Yb and La) sandwiches with diethylene-glycol-disubstituted porphyrins (DD) are reported, with their structures proven by both quantum chemical calculations and scanning tunneling microscopy. Our findings demonstrate that the near-infrared emission intensity and singlet oxygen (¹O₂) quantum yields of YbDD and GdDD in aqueous media are higher than those of the reported capped lanthanide monoporphyrinato analogues, YbN and GdN; the brightness and luminescence lifetime in water of YbDD are greater than those of YbN. This work provides a new dimension for the future design and development of molecular theranostics-based water-soluble double-decker lanthanide bisporphyrinates.

A new class of rare earth tetrapyrrole sandwich complexes containing corrole and phthalocyanine macrocycles: synthesis, physicochemical characterization and X-ray analysis

The first europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles was synthesized and characterized by spectroscopic and electrochemical methods. The molecular structure was characterized by single-crystal X-ray diffraction and showed the corrole to be in the middle of the sandwich with phthalocyanine macrocycles at each extreme.

Regiospecific synthesis of lanthanum(III) and neodymium(III) triple-decker (tetrakis-meso-(3-bromophenyl)-porphyrinato)(crownphthalocyaninates)

The triple-decker complexes of symmetrical type [m Br 4 TPP ] Ln [(15 C 5)4 Pc ] Ln [m Br 4 TPP ] ( Ln -m TD ; Ln = La , Nd ; [(15 C 5)4 Pc ] = tetra-(15-crown-5)-phthalocyaninato-ligand; [m Br 4 TPP ] = tetrakis-meso-(3-bromophenyl)-porphyrinato-ligand) are synthesized for the first time with 43% and 36% yield. The applicability of the previously developed selective one-step synthetic approach for the preparation of the mentioned complexes is demonstrated and the limitations, determined by meta-substitution of meso-aryl-fragments, are revealed. The spectral features of the obtained complexes is determined by means of UV-vis and NMR spectroscopy. The hindered rotation of porphyrin meso-substituents in the obtained complexes and formation of statistical set of atropisomers are demonstrated.