Design, Formation and Properties of Tetrahedral M4L4and M4L6Supramolecular Clusters1

Caulder, Dana L.; Brückner, Christian; Powers, Ryan E.; König, S.; Parac, Tatjana N.; Leary, Julie A.; Raymond, Kenneth N.

doi:10.1021/ja0104507

Cited by 271 publications

(213 citation statements)

References 76 publications

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“…There have been previous examples of stimuli-responsive molecular cages (41,61) and baskets (45)(46)(47)(48)(49)(50)(51)(52)62) for targeted delivery; however, most of the systems lack the spontaneous spectral or other kinds of responses to facilitate instant signal detection. In contrast, the guest release and capture processes of the current molecular rectangles are capable of being probed by UV-vis absorption and emission titration studies.…”

Section: Resultsmentioning

confidence: 99%

Multiaddressable molecular rectangles with reversible host–guest interactions: Modulation of pH-controlled guest release and capture

Chan

Lam

Tanaka

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

122

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A series of multiaddressable platinum(II) molecular rectangles with different rigidities and cavity sizes has been synthesized by endcapping the U-shaped diplatinum(II) terpyridine moiety with various bisalkynyl ligands. The studies of the host-guest association with various square planar platinum(II), palladium(II), and gold(III) complexes and the related low-dimensional gold(I) complexes, most of which are potential anticancer therapeutics, have been performed. Excellent guest confinement and selectivity of the rectangular architecture have been shown. Introduction of pH-responsive functionalities to the ligand backbone generates multifunctional molecular rectangles that exhibit reversible guest release and capture on the addition of acids and bases, indicating their potential in controlled therapeutics delivery on pH modulation. The reversible host-guest interactions are found to be strongly perturbed by metal-metal and π-π interactions and to a certain extent, electrostatic interactions, giving rise to various spectroscopic changes depending on the nature of the guest molecules. Their binding mode and thermodynamic parameters have been determined by 2D NMR and van't Hoff analysis and supported by computational study. noncovalent interactions | platinum complex | luminescence T he study of metal-metal interactions has drawn enormous attention since the past two decades because of the intriguing spectroscopic and photophysical properties arising from the close proximity of the metal centers (1, 2). Square planar d 8 platinum(II) complexes with coordination unsaturation are one of the important classes of metal complexes that have been extensively explored because of their capability to exhibit metalmetal interactions and display rich photophysical properties (3-26). Platinum(II) terpyridine complexes have been found to exhibit rich polymorphism in the solid state (16)(17)(18)(19)(20) owing to their square planar coordination geometry, which permits facile access to Pt(II)···Pt(II) interactions as well as π-π interactions between the chromophores. It was not until 2001 that the first successful synthesis of platinum(II) terpyridine alkynyl complexes, which possess enhanced solubility and luminescence compared with the chloro counterpart, was reported (16). Additional efforts have been devoted to the use of the system to respond to external stimuli, such as variation in solvent composition (17, 18), pH (19, 20), temperature (21, 22), addition of ionic (24-26), and polymeric species (27,28), in which spectral changes induced by strong Pt(II)···Pt(II) and π−π interactions have been displayed.In the past few decades, enormous efforts have been devoted to the construction of molecular architectures by fusing the organic framework to the transition metal centers through selfassembly processes (29-57). There has been continuous interest in the construction of stimuli-responsive metallosupramolecular architectures with diverse sizes, shapes, and symmetries to rationalize the criteria for molecular recognition and impa...

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Section: Resultsmentioning

confidence: 99%

Multiaddressable molecular rectangles with reversible host–guest interactions: Modulation of pH-controlled guest release and capture

Chan

Lam

Tanaka

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

122

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“…Supramolecular lanthanide complexes have been reviewed by Bünzli and Piguet. [83] For supramolecular d-block metals, the concept of "incommensurate coordination number" was developed, [84][85][86][87][88] a term that relates to preferred coordination geometries of metal centers and rigid ligands with a defined angle between chelating groups. Lanthanides are more flexible with regard to preferred coordination geometries than transition metals, properties that are especially important for Gd-based MRI contrast agents (which are at the border of favoring eight or nine coordinate geometries, as discussed above).…”

Section: Fe/gd Supramolecular Complexesmentioning

confidence: 99%

High‐Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

et al. 2008

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“…10,12,17,18 Raymond and coworkers have developed a series of self-assembled supramolecular metal-ligand assemblies of M 4 L 6 stoichiometry (M = Ga 3+ (1), Al 3+ , Fe 3+ ; L = N,N′-bis (2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene). [19][20][21][22] The four trivalent metal atoms are located at the vertices of the tetrahedron, while naphthalene-based bis-bidentate catechol ligands span the edges, forming a T-symmetric, cavitycontaining assembly (Figure 1). Strong mechanical coupling between the metal vertices through the ligands enforces self-assembly of a racemic mixture of the homochiral ΔΔΔΔ and ΛΛΛΛ configurations.…”

Section: Introductionmentioning

confidence: 99%

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled “Nanozyme”

et al. 2008

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Design, Formation and Properties of Tetrahedral M₄L₄and M₄L₆Supramolecular Clusters¹

Cited by 271 publications

References 76 publications

Multiaddressable molecular rectangles with reversible host–guest interactions: Modulation of pH-controlled guest release and capture

Multiaddressable molecular rectangles with reversible host–guest interactions: Modulation of pH-controlled guest release and capture

High‐Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled “Nanozyme”

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