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Self-assembly of metallointercalators into DNA nanocages is a rapid and facile approach to synthesizing discrete bioinorganic host:guest structures with a high load of metal complexes. Turberfield’s DNA tetrahedron can accommodate one intercalator for every two base pairs, which corresponds to 48 metallointercalators per DNA tetrahedron. The affinity of the metallointercalator for the DNA tetrahedron is a function of both the structure of the intercalating ligand and the overall charge of the complex, with a trend in affinity [Ru(bpy)(2)(dppz)](2+) > [Tb-DOTAm-Phen](3+) >> Tb-DOTA-Phen. Intercalation of the metal complex stabilizes the DNA tetrahedron resulting in an increase of its melting temperature and, importantly, a significant increase in its stability in the presence of serum. [Ru(bpy)(2)(dppz)](2+), which has a greater affinity for DNA than [Tb-DOTAm-Phen](3+), increases the melting point and decreases degradation in serum to a greater extent than the Tb(III) complex. In the presence of lipofectamine, the metallointercalator@DNA nanocage assemblies substantially increases the cell uptake of their respective metal complex. Altogether, the facile incorporation of a large number of metal complex per assembly, the higher stability in serum, and the increased cell penetration of metallointercalator@DNA make these self-assemblies well-suited as metallodrugs.

Despite its prevalence in the environment, the chemistry of the Ti

Thermodynamically favored simultaneous coordination of Pt(ii) corners with aza- and carboxylate ligands yields tricomponent coordination complexes with sophisticated structures and functions, which require careful structural characterization to paint accurate depiction of their structure-function relationships. Previous reports claimed that heteroleptic coordination of

N-acylhydrazones 2-(4-chlorophenyl)-N0 -(2-hydroxybenzylidene)acetohydrazide, N0 -(2-hydroxybenzylidene)-2-(4-methoxyphenyl)acetohydrazide, 2-(4-chlorophenyl)-N0 -(2,4-dihydroxybenzylidene)-acetohydrazide, and N0 -(2,4-dihydroxybenzylidene)-2-(4-methoxyphenyl)acetohydrazide were successfully synthesized by a multistep procedure. The obtained organic molecules were characterized by spectroscopic techniques (FT-IR, 1D and 2D NMR, UV-Vis) and mass spectrometry. The structure of 2-(4-chlorophenyl)-N0 -(2-hydroxybenzylidene)acetohydrazide was also confirmed by X-ray diffraction. Ab initio computational simulations of the ligand spectra were in good agreement with experimental data and validated the hypothesis about the existence of a conformational mixture of each ligand in solution. Finally, the complexation potential of the synthesized ligands to Cu2+ was assessed by continuous variation experiments and FT-IR spectroscopy.

Thermodynamically favored heteroleptic coordination of Pt(II) ions with one aza- and another oxo-coordinating ligand yield tricomponent supramolecular coordination complexes (SCCs), which possess much greater structural complexity and functional diversity than traditional bicomponent SCCs containing only one of the ligands. Through X-ray crystallography, 1H, 31P, and 2D NMR spectroscopies, mass spectrometry, and computational studies, herein, we demonstrated that heteroleptic coordination of tetrapyridyl porphyrins (MTPP, M = Zn or H2) and various dicarboxylate ligands (XDC) having different lengths and rigidity with cis-(Et3P)2PtII corners yielded bow-tie (⋈)-shaped tricomponent [{cis-(Et3P)2Pt}4(MTPP)(XDC)2]4+ complexes featuring a MTPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners and ruled out the MTPP-based tetragonal prism formation. Irrespective of the rigidity and length of the XDC linkers within a certain range (~7–11 Å), they intramolecularly bridged two adjacent pyridyl tips of an MTPP ligand via PtII(N,O) corners, which led to the formation of bow-tie complexes instead of prisms. This happened because the angles of projection between the adjacent pyridyl rings of MTPP cores adapted to accommodate the bridging XDC linkers having different lengths, and the bow-tie formation was entropically favored over tetragonal prisms. This work not only unveiled novel bow-tie-shaped coordination complexes, but also accurately defined the actual structures and compositions of MTPP-based tricomponent SCCs. Furthermore, a representative bow-tie complex containing an electron-rich ZnTPP core selectively formed a charge-transfer (CT) complex with highly electron deficient 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-heaxacarbonitrile (HATHCN) but not with π-donors like pyrene.

Thermodynamically favored heteroleptic coordination of one aza- and another oxo-coordinating ligand with Pt(II) ions yield tricomponent supramolecular coordination complexes (SCCs) that have much greater structural complexity and functional diversity than the traditional bicomponent SCCs containing only one of the ligands. Herein, we demonstrate that heteroleptic coordination of tetrapyridyl porphyrins (M¢TPP, M¢ = Zn or H2) and various dicarboxylate ligands (XDC) having different lengths and rigidity with cis- (Et3P)2PtII corners actually yields bow tie (⋈)-shaped tricomponent [{cis-(Et3P)2Pt}4(M¢TPP)(XDC)2] 4+ complexes featuring a M¢TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. Although previous reports have claimed that the self-assembly of these three components produced tetragonal prisms having two cofacial M¢TPP planes connected by four XDC linkers via eight PtII(N,O) corners, our extensive 1 H, 31P, and 2D NMR, ESI-MS, X-ray crystallographic, and computational studies unequivocally demonstrated that in reality, no such prism was formed because instead of connecting two cofacial M¢TPP ligands, the XDC linkers actually bridged two adjacent pyridyl termini of an M¢TPP ligand via shared PtII(N,O) corners, forming bow tie complexes. In addition to direct crystallographic evidence, the NMR spectra of these complexes revealed that the M¢TPP ligands contained two distinct pyrrole protons (4 each)—those located inside the triangles were shielded by and coupled to adjacent XDC linkers, whereas the exposed ones were not—an unmistakable sign of their bow tie structures. Thus, this work not only unveiled novel bow tie-shaped coordination complexes, but also accurately defined the actual structures and compositions of M¢TPP-based tricomponent SCCs.

Four tris-bidentate catecholamide (CAM) ligands were synthesized, characterized, and evaluated as ligands for radiolabeling of gallium-68 for positron emission tomography (PET). Three of those ligands, 2,2-Glu-CAM, 3,3-Glu-CAM, and TREN-bisGlyGlu-CAM, incorporate ligand caps that contain a pendant carboxylic group for further conjugation to targeting moieties. The acyclic ligands all exhibited high (>80%) radiolabeling yields after short reaction times ( 24, although the functionalizable ligands are less stable than the parent GaIII-TREN-CAM. In vivo imaging studies and ex vivo pharmacokinetic and biodistribution studies indicate that the parent [68Ga]Ga-TREN-CAM is stable in vivo but is rapidly cleared in 95%) render TREN-bisGlyGlu-CAM a promising candidate for gallium-68 chelation.