Luminescent Platinum(<scp>II</scp>) Terpyridyl Complexes: Effect of Counter Ions on Solvent‐Induced Aggregation and Color Changes

Yam, Vivian Wing‐Wah; Chan, Kalok; Wong, Keith Man‐Chung; Zhu, Nianyong

doi:10.1002/chem.200500106

Cited by 213 publications

(129 citation statements)

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“…(Higher oligomers could not be observed in the ESI-MS experiments because their m/z values are beyond the detection range of our instrument.) In addition, a very weak emission band at Ϸ800 nm also starts to appear at Ϸ15 M complex concentration, and its intensity becomes stronger with increasing complex concentrations, probably ascribed to an excited state of a triplet metal-metal-to-ligand charge transfer ( 3 MMLCT) origin based on previous studies on related systems (17)(18)(19)(20)(21). Nevertheless, at a 30 M complex concentration, which is used throughout the current investigation, the 800 nm background emission bands are very weak and just barely recognizable for both complexes.…”

Section: Resultsmentioning

confidence: 72%

“…Recently, we have synthesized a number of platinum(II) polypyridyl alkynyl complexes that show interesting spectroscopic and luminescence properties (17)(18)(19)(20)(21). One particularly interesting observation is that solvents of different polarity and also polyacrylate could induce the aggregation of the positively charged platinum complexes in organic solvent mixtures (19,21).…”

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confidence: 99%

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Single-stranded nucleic acid-induced helical self-assembly of alkynylplatinum(II) terpyridyl complexes

Chan

Wong

et al. 2006

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

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Single-stranded nucleic acids, which carry multiple negative charges in an aqueous medium at near neutral pH, are found to induce the aggregation and self-assembly of the positively charged alkynylplatinum(II) terpyridyl complexes via electrostatic binding of the platinum complexes to the single-stranded nucleic acids, as revealed by the appearance of new UV-vis absorption and emission bands upon addition of single-stranded nucleic acids to a buffer solution of the complex. Changes in the intensity and pattern of circular dichroism (CD) spectroscopy are also observed, many of which are consistent with the assembly of the platinum complexes into helical structures, via metal⅐⅐⅐metal and ⅐⅐⅐ stacking interactions. The induced spectroscopic property changes are found to depend on the structural properties of the nucleic acids.helicity ͉ noncovalent interactions ͉ platinum complex N ucleic acids are, in a sense, the most fundamental and important class of biomolecules in a living cell. Detection of nucleic acids, analysis of their sequence, structure, and the corresponding properties, as well as their self-replication, interactions with regulation factors, and the details of transcription and translation are among the major foci of numerous biochemical and biophysical research works (1, 2). Single-stranded nucleic acid sensing and characterization are therefore of great importance, which not only can help us to understand how the cell functions and to assist biological research, but also facilitate the development of new tools for disease diagnosis and treatment and new drug developments.It has been known for many years that many of the square planar metal complexes arrange themselves into highly ordered extended linear chain or oligomeric structures in the solid state. Depending on the extent of the metal⅐⅐⅐metal and the ligand ⅐⅐⅐ stacking interactions, different colors could be observed (3, 4). Square planar platinum(II) complexes belong to a particularly interesting class of this type of complexes, as a result of their rich spectroscopic and luminescence properties revealed during the past few decades (3-16).Recently, we have synthesized a number of platinum(II) polypyridyl alkynyl complexes that show interesting spectroscopic and luminescence properties (17-21). One particularly interesting observation is that solvents of different polarity and also polyacrylate could induce the aggregation of the positively charged platinum complexes in organic solvent mixtures (19, 21). As a result, remarkable spectroscopic property changes were observed. Because single-stranded nucleic acids carry multiple negatively charged phosphate functional groups, they are polyanions. It is therefore reasonable to envisage that single-stranded nucleic acids may have the possibility to induce the self-assembly of the square planar platinum(II) complexes in an aqueous environment. Here, we describe the synthesis and characterization of a water-soluble platinum(II) terpyridyl alkynyl complex, [Pt(tpy)C'CC'CCH 2 OH]OTf (1) (Fig. 1), and it...

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Section: Resultsmentioning

confidence: 72%

mentioning

confidence: 99%

Single-stranded nucleic acid-induced helical self-assembly of alkynylplatinum(II) terpyridyl complexes

Chan

Wong

et al. 2006

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

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124

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“…The electronic absorption spectra of alkynylplatinum(II) terpyridine molecular rectangles 1−4 in dichloromethane solution at room temperature displayed intense intraligand [π → π*] transitions of the terpyridine and the alkynyl ligands at 250−345 nm together with the moderately intense absorptions at 420−490 nm, which are assigned as admixtures of metal-to-ligand charge transfer (MLCT) [dπ(Pt) → π*(terpyridine)] and ligand-to-ligand charge transfer (LLCT) [π(C≡CR) → π*(terpyridine)] transitions according to previous spectroscopic studies on alkynylplatinum(II) terpyridine systems (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). Molecular rectangles 1−4 in degassed acetonitrile solution and solid state at 298 K exhibited structure-less emission bands at 620−700 nm, which are tentatively assigned as originated from the 3 MLCT/ 3 LLCT [dπ(Pt)/ π(C≡CR) → π*(terpyridine)] excited state with similar trends to their electronic absorptions.…”

Section: Resultsmentioning

confidence: 99%

“…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 . 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).…”

mentioning

confidence: 99%

“…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)(25)(26), and polymeric species (27,28), in which spectral changes induced by strong Pt(II)···Pt(II) and π−π interactions have been displayed.…”

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confidence: 99%

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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.

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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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Vapochromic and Vapoluminescent Sensors: Optical Versions of Electronic Noses

Chatterjee,

Norton,

Krause

et al. 2023

Organic and Inorganic Materials Based Sensors

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Luminescent Platinum(II) Terpyridyl Complexes: Effect of Counter Ions on Solvent‐Induced Aggregation and Color Changes

Cited by 213 publications

References 45 publications

Single-stranded nucleic acid-induced helical self-assembly of alkynylplatinum(II) terpyridyl complexes

Single-stranded nucleic acid-induced helical self-assembly of alkynylplatinum(II) terpyridyl complexes

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

Vapochromic and Vapoluminescent Sensors: Optical Versions of Electronic Noses

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