Ruthenium(II)-bis(4'-(4-ethynylphenyl)-2,2':6', 2''-terpyridine) - A versatile synthon in supramolecular chemistry. Synthesis and characterization

A homoleptic ethynyl-substituted ruthenium(II)-bisterpyridine complex representing a versatile synthon in supramolecular chemistry was synthesized and analyzed by NMR spectroscopy, mass spectrometry and X-ray diffractometry. Furthermore, its photophysical properties were detailed by UV/Vis absorption, emission and resonance Raman spectroscopy. In order to place the results obtained in the context of the vast family of ruthenium coordination compounds, two structurally related complexes were investigated accordingly. These reference compounds bear either no or an increased chromophore in the 4̀-position. The spectroscopic investigations reveal a systematic bathochromic shift of the absorption and emission maximum upon increasing chromophore size. This bathochromic shift of the steady state spectra occurs hand in hand with increasing resonance Raman intensities upon excitation of the metal-to-ligand charge-transfer transition. The latter feature is accompanied by an increased excitation delocalization over the chromophore in the 4̀-position of the terpyridine. Thus, the results presented allow for a detailed investigation of the electronic effects of the ethynyl substituent on the metal-to-ligand charge-transfer states in the synthon for click reactions leading to coordination polymers

It takes three to tango: The length of the oligothiophene chain determines the nature of the long‐lived excited state and the resulting photocytotoxicity of a ruthenium(II) Photodrug

Abstract TLD1433 is the first Ru(II) complex to be tested as a photodynamic therapy agent in a clinical trial. In this contribution we study TLD1433 in the context of structurally‐related Ru(II)‐imidozo[4,5‐f][1,10]phenanthroline (ip) complexes appended with thiophene rings to decipher the unique photophysical properties which are associated with increasing oligothiophene chain length. Substitution of the ip ligand with ter‐ or quaterthiophene changes the nature of the long‐lived triplet state from metal‐to‐ligand charge‐transfer to 3 ππ* character. The addition of the third thiophene thus presents a critical juncture which not only determines the photophysics of the complex but most importantly its capacity for 1 O 2 generation and hence the potential of the complex to be used as a photocytotoxic agent

Multimodal nonlinear imaging of atherosclerotic plaques differentiation of triglyceride and cholesterol deposits

Cardiovascular diseases in general and atherothrombosis as the most common of its individual disease entities is the leading cause of death in the developed countries. Therefore, visualization and characterization of inner arterial plaque composition is of vital diagnostic interest, especially for the early recognition of vulnerable plaques. Established clinical techniques provide valuable morphological information but cannot deliver information about the chemical composition of individual plaques. Therefore, spectroscopic imaging techniques have recently drawn considerable attention. Based on the spectroscopic properties of the individual plaque components, as for instance different types of lipids, the composition of atherosclerotic plaques can be analyzed qualitatively as well as quantitatively. Here, we compare the feasibility of multimodal nonlinear imaging combining two-photon fluorescence (TPF), coherent anti-Stokes Raman scattering (CARS) and second-harmonic generation (SHG) microscopy to contrast composition and morphology of lipid deposits against the surrounding matrix of connective tissue with diffraction limited spatial resolution. In this contribution, the spatial distribution of major constituents of the arterial wall and atherosclerotic plaques like elastin, collagen, triglycerides and cholesterol can be simultaneously visualized by a combination of nonlinear imaging methods, providing a powerful label-free complement to standard histopathological methods with great potential for in vivo application

Photophysical Study on the Rigid Pt(II) Complex [Pt(naphen)(Cl)] (Hnaphen = Naphtho[1,2-b][1,10]Phenanthroline and Derivatives

The electrochemistry and photophysics of the Pt(II) complexes [Pt(naphen)(X)] (Hnaphen = naphtho[1,2-b][1,10]phenanthroline, X = Cl or C≡CPh) containing the rigid tridentate C^N^N-coordinating pericyclic naphen ligand was studied alongside the complexes of the tetrahydro-derivative [Pt(thnaphen)(X)] (Hthnaphen = 5,6,8,9-tetrahydro-naphtho[1,2-b][1,10]phenanthroline) and the N^C^N-coordinated complex [Pt(bdq)(Cl)] (Hbdq = benzo[1,2-h:5,4-h’]diquinoline. The cyclic voltammetry showed reversible reductions for the C^N^N complexes, with markedly fewer negative potentials (around −1.6 V vs. ferrocene) for the complexes containing the naphen ligand compared with the thnaphen derivatives (around −1.9 V). With irreversible oxidations at around +0.3 V for all of the complexes, the naphen made a difference in the electrochemical gap of about 0.3 eV (1.9 vs. 2.2 eV) compared with thnaphen. The bdq complex was completely different, with an irreversible reduction at around −2 V caused by the N^C^N coordination pattern, which lacked a good electron acceptor such as the phenanthroline unit in the C^N^N ligand naphen. Long-wavelength UV-Vis absorption bands were found around 520 to 530 nm for the C^N^N complexes with the C≡CPh coligand and were red-shifted when compared with the Cl derivatives. The N^C^N-coordinated bdq complex was markedly blue-shifted (493 nm). The steady-state photoluminescence spectra showed poorly structured emission bands peaking at around 630 nm for the two naphen complexes and 570 nm for the thnaphen derivatives. The bdq complex showed a pronounced vibrational structure and an emission maximum at 586 nm. Assuming mixed 3LC/3MLCT excited states, the vibronic progression for the N^C^N bdq complex indicated a higher LC character than assumed for the C^N^N-coordinated naphen and thnaphen complexes. The blue-shift was a result of the different N^C^N vs. C^N^N coordination. The photoluminescence lifetimes and quantum yields ΦL massively increased from solutions at 298 K (0.06 to 0.24) to glassy frozen matrices at 77 K (0.80 to 0.95). The nanosecond time-resolved study on [Pt(naphen)(Cl)] showed a phosphorescence emission signal originating from the mixed 3LC/3MLCT with an emission lifetime of around 3 µs

Multifunctional Polyoxometalate Platforms for Supramolecular Light-Driven Hydrogen Evolution

Multifunctional supramolecular systems are a central research topic in light-driven solar energy conversion. Here, we report a polyoxometalate (POM)-based supramolecular dyad, where two platinum-complex hydrogen evolution catalysts are covalently anchored to an Anderson polyoxomolybdate anion. Supramolecular electrostatic coupling of the system to an iridium photosensitizer enables visible light-driven hydrogen evolution. Combined theory and experiment demonstrate the multifunctionality of the POM, which acts as photosensitizer/catalyst-binding-site[1] and facilitates light-induced charge-transfer and catalytic turnover. Chemical modification of the Pt-catalyst site leads to increased hydrogen evolution reactivity. Mechanistic studies shed light on the role of the individual components and provide a molecular understanding of the interactions which govern stability and reactivity. The system could serve as a blueprint for multifunctional polyoxometalates in energy conversion and storage

Intracellular Photophysics of an Osmium Complex bearing an Oligothiophene Extended Ligand

This contribution describes the excited-state properties of an Osmium-complex when taken up into human cells. The complex 1 [Os(bpy)2(IP-4T)](PF6)2 with bpy=2,2′-bipyridine and IP-4T=2-{5′-[3′,4′-diethyl-(2,2′-bithien-5-yl)]-3,4-diethyl-2,2′-bithiophene}imidazo[4,5-f][1,10]phenanthroline) can be discussed as a candidate for photodynamic therapy in the biological red/NIR window. The complex is taken up by MCF7 cells and localizes rather homogeneously within in the cytoplasm. To detail the sub-ns photophysics of 1, comparative transient absorption measurements were carried out in different solvents to derive a model of the photoinduced processes. Key to rationalize the excited-state relaxation is a long-lived 3ILCT state associated with the oligothiophene chain. This model was then tested with the complex internalized into MCF7 cells, since the intracellular environment has long been suspected to take big influence on the excited state properties. In our study of 1 in cells, we were able to show that, though the overall model remained the same, the excited-state dynamics are affected strongly by the intracellular environment. Our study represents the first in depth correlation towards ex-vivo and in vivo ultrafast spectroscopy for a possible photodrug. © 2020 The Authors. Published by Wiley-VCH Gmb

In Older Patients Treated for Dizziness and Vertigo in Multimodal Rehabilitation Somatic Deficits Prevail While Anxiety Plays a Minor Role Compared to Young and Middle Aged Patients

Objective: Many patients with dizziness and vertigo are of older age. It is still unclear which age-associated factors play a role in the treatment of dizziness and vertigo. Therefore, age-associated characteristics of patients subjected to an interdisciplinary day care approach for chronic vertigo and dizziness were analyzed.Subjects and Methods: 650 patients with chronic dizziness/vertigo subjected to a multimodal vestibular rehabilitation day care program were analyzed. Information concerning age, gender, medical diagnosis, medical consultations, technical diagnostics performed and therapy achieved before attending the clinic were collected. Furthermore, data were gathered using the Vertigo Severity Scale (VSS), Hospital Anxiety and Depression Scale (HADS), Mobility Inventory (MI), as well as the intensity of and the distress due to vertigo/dizziness using visual analog scales. As a follow-up, the VSS, HADS, MI, and the visual analog scales were collected again 6 months after attending the therapy program. Three age groups were compared to each other (<41, 41–65, and >65 years of age).Results: One-third of the patients were older than 65 years. This group had typical diagnoses with mainly organic deficits. In contrast to the dominance of mainly multifactorial, organic deficits the older patients reported less medical consultations, fewer technical diagnostics and even fewer treatments than the younger patients. The elderly scored significantly lower in total VSS, in VSS-V (vestibular-balance subscale), in VSS-A (autonomic-anxiety subscale) and in HADS-anxiety. Psychological diagnoses were clearly associated to the younger patients. 424 patients (65.2%) completed the follow-up questionnaire 6 months after attending the therapy week. The older patients revealed improvements of VSS-V and the Avoidance Alone scale of MI as well as decreased distress due to vertigo/dizziness.Conclusion: In the older patients, who took part in our vestibular rehabilitation program, mainly somatic deficits prevail while anxiety plays a minor role compared to young and middle aged patients. Older patients profited from vestibular rehabilitation especially in mobility and vestibular-balance. Therefore, vestibular rehabilitation programs for the elderly with a focus on physio- and occupational therapeutic interventions and less cognitive behavioral therapy may be reasonable

Triplet-triplet annihilation upconversion for calcium sensing

Triplet-triplet annihilation upconversion is a bimolecular process converting low-energy light into high-energy one. All available calcium probes, despite their qualities, are downconverting, which leads to the autofluorescence caused by background emission of the intra- and intercellular molecules. Here we report a calcium-sensing system working via upconverted emission. The probe itself was obtained by covalent conjugation of a perylene blue emitter with a calcium-chelating moiety; it was sensitized by a red-light absorbing palladium porphyrin. Sensing was selective towards Ca2+ and occurred in the micromolar domain in aqueous solutions and methanol. The upconverted luminescence only appeared in the presence of calcium ions, with a quantum yield of up to 0.0018

Spectroscopic Investigation of the Ultrafast Photoinduced Dynamics in pi-Conjugated Terpyridines

Time-resolved spectroscopy is applied to investigate the ultrafast relaxation dynamics of several pi-conjugated mono-, bis-, tris- and tetrakis(terpyridine) derivs. This particular series of structurally closely related systems was prepd. applying efficient synthetic strategies and resembles key building blocks for a wide range of photoactive complexes, dendrimers and metallo-polymers with resulting potential applications, for example, in photovoltaics or as org. light-emitting diodes. Aiming for applications of supramol. assemblies based on these recently presented terpyridine ligands a detailed knowledge of the light-induced processes of the ligands themselves represents a prerequisite. By applying femtosecond time-resolved absorption spectroscopy in concert with time-resolved fluorescence and Raman measurements, we detail the photophys. properties. [on SciFinder (R)