Stepwise Modulation of Bridged Single-Benzene-Based Fluorophores for Materials Science.

In recent years, researchers studying fluorogenic samples have steadily shifted from using large, expensive, poorly soluble fluorophores with complex synthetic sequences to smaller, simpler p scaffolds with low molecular weight. This research article presents an in-depth study of the photophysical properties of five bridged single-benzene-based fluorophores (SBBFs) investigated for their solution and solid-state emission (SSSE) properties. The compounds O4, N1O3, N2O2, N3O1, and N4 are derived from a central terephthalonitrile core and vary in the amount of oxygen and nitrogen bridging atoms.

Photoresponsive Luminescent Silica Nanoparticles as Additive for 3D Printing and Electrospinning.

In this study, we present the synthesis and a versatile way to incorporate photoresponsive organic luminophores into polymeric materials using mesoporous silica nanoparticles (MSNs). The encapsulated thioethers within the MSNs were employed in polyvinyl alcohol (PVA) films, resin-based stereolithography, and electrospinning. Due to light-induced cyclisation to dibenzothiophenes (DBTs), mmOC loaded materials were used to inscribe images using UV light.

In situ Cyclization of Aromatic Thioethers in Emissive Materials to Generate Phosphorescent Dibenzothiophenes.

In this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV-light without any need for additives. This cost-effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized by X-ray crystallography and state-of-the-art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices.

Merging of a Supramolecular Ligand with a Switchable Luminophore - Light-Responsiveness, Photophysics and Bioimaging.

In this contribution we report on a novel approach towards luminescent light-responsive ligands. To this end, cyanostilbene- guanidiniocarbonyl-pyrrole hybrids were designed and investigated. Merging of a luminophore with a supramolecular bioactive ligand bears numerous advantages by overcoming the typical drawbacks of drug-labelling, influencing the overall performance of the active species by attachment of a large luminophore.

Functional Linkers Support Targeting of Multivalent Tweezers to Taspase1.

Taspase 1 is a unique protease not only pivotal for embryonic development but also implicated in leukemias and solid tumors. As such, this enzyme is a promising while still challenging therapeutic target, and with its protein structure featuring a flexible loop preceding the active site a versatile model system for drug development. Supramolecular ligands provide a promising complementary approach to traditional small-molecule inhibitors.

Pt(II) Complexes with Tetradentate C^N*N^C Luminophores: From Supramolecular Interactions to Temperature-Sensing Materials with Memory and Optical Readouts.

A series of four regioisomeric Pt(II) complexes ( and ) bearing tetradentate luminophores as dianionic ligands were synthesized. Hence, both classes of cyclometallating chelators were decorated with three -hexyl ( = 6) or -dodecyl ( = 12) chains. The new compounds were unambiguously characterized by means of multiple NMR spectroscopies and mass spectrometry.

Deoxyestrone-based lipofection agents with solution- and solid-state emission properties.

In this contribution, three deoxyestrone-based emissive lipofection agents are reported. Because of a centrally incorporated terephthalonitrile motif, these ligands can be classified as solution and solid-state emitters (SSSEs). With the attachment of tobramycin, these amphiphilic structures are able to form lipoplexes, mediating gene transfection of HeLa and HEK 293T cells.

Cationic Solution and Solid-State Emitters - Robust Imaging Agents for Cells, Bacteria, and Protists.

A library of eight different cationic emitters with emission properties in solution and in solid-state (solution and solid-state emitters - SSSE) is presented. These compounds, bearing either ammonium or pyridinium groups, have been investigated regarding their photophysical properties as well as their potential application in biological imaging. Besides high quantum yields as well as a high degree of stability during the imaging process, it was additionally revealed that a broad range of biological targets can be addressed, such as different bacterial strains, human cells as well as protists.

Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups.

The 14-3-3 protein family, one of the first discovered phosphoserine/phosphothreonine binding proteins, has attracted interest not only because of its important role in the cell regulatory processes but also due to its enormous number of interactions with other proteins. Here, we use a computational approach to predict the binding sites of the designed hybrid compound featuring aggregation-induced emission luminophores as a potential supramolecular ligand for 14-3-3ζ in the presence and absence of C-Raf peptides. Our results suggest that the area above and below the central pore of the dimeric 14-3-3ζ protein is the most probable binding site for the ligand.

Design Concepts for Solution and Solid-State Emitters - A Modern Viewpoint on Classical and Non-Classical Approaches.

For a long time, luminescence phenomena were strictly distinguished between the emission of isolated molecules in dilute solutions or close-packed structures such as in powders or aggregates. This changed with the breakthrough observation of dual-state efficient materials, which led to a rapid boost of publications examining the influence of structural features to achieve balanced emission with disregarded molecular surroundings. Some first general structural design concepts have already been proposed based on reoccurring patterns and pivotal motifs.

Total Synthesis of Resveratrone and iso-Resveratrone.

The first total synthesis of resveratrone and iso-resveratrone based on an epoxide olefination approach is described. The pivotal reaction proceeds by insertion of the lithiated epoxide into a boronic ester and subsequent syn-elimination. Resveratrone has been described to have remarkable photophysical properties, including two-photon absorption.

Phosphorescence Induction by Host-Guest Complexation with Cyclodextrins - The Role of Regioisomerism and Affinity.

We present an in-depth investigation of cyclodextrin complexes with guest compounds featuring complexation-induced room temperature phosphorescence (RTP) in aqueous solution. Very interestingly, only the complexed regioisomers bearing lateral substituents on meta-position show RTP, whereas the stronger host-guest systems with para-substituted dyes show no RTP features. The reported systems were investigated regarding their complexation behavior in water using isothermal titration calorimetry and mass spectrometry.

Evolution of Artificial Arginine Analogues-Fluorescent Guanidiniocarbonyl-Indoles as Efficient Oxo-Anion Binders.

In this article, we present fluorescent guanidiniocarbonyl-indoles as versatile oxo-anion binders. Herein, the guanidiniocarbonyl-indole (GCI) and methoxy-guanidiniocarbonyl-indole (MGCI) were investigated as ethylamides and compared with the well-known guanidiniocarbonyl-pyrrole (GCP) concerning their photophysical properties as well as their binding behavior towards oxo-anions. Hence, a variety of anionic species, such as carboxylates, phosphonates and sulfonates, have been studied regarding their binding properties with GCP, GCI and MGCI using UV-Vis titrations, in combination with the determination of the complex stoichiometry using the Job method.

Covalent Attachment of Aggregation-Induced Emission Molecules to the Surface of Ultrasmall Gold Nanoparticles to Enhance Cell Penetration.

Three different alkyne-terminated aggregation-induced emission molecules based on a -substituted di-thioether were attached to the surface of ultrasmall gold nanoparticles (2 nm) by copper-catalyzed azide-alkyne cycloaddition (click chemistry). They showed a strong fluorescence and were well water-dispersible, in contrast to the dissolved AIE molecules. The AIE-loaded nanoparticles were not cytotoxic and easily penetrated the membrane of HeLa cells, paving the way for an intracellular application of AIE molecules, e.

Mapping the Regioisomeric Space and Visible Color Range of Purely Organic Dual Emitters with Ultralong Phosphorescence Components: From Violet to Red Towards Pure White Light.

We mapped the entire visible range of the electromagnetic spectrum and achieved white light emission (CIE: 0.31, 0.34) by combining the intrinsic ns-fluorescence with ultralong ms-phosphorescence from purely organic dual emitters.

A Bivalent Supramolecular GCP Ligand Enables Blocking of the Taspase1/Importin α Interaction.

Taspase1 is a unique protease not only pivotal for embryonic development but also implicated in leukemia as well as solid tumors. As such, it is a promising target in cancer therapy, although only a limited number of Taspase1 inhibitors lacking general applicability are currently available. Here we present a bivalent guanidiniocarbonyl-pyrrole (GCP)-containing supramolecular ligand that is capable of disrupting the essential interaction between Taspase1 and its cognate import receptor Importin α in a concentration-dependent manner in vitro with an IC of 35 μM.

Umbelliferone Decorated Water-soluble Zinc(II) Phthalocyanines - In Vitro Phototoxic Antimicrobial Anti-cancer Agents.

In this contribution we report on the synthesis, characterization and application of water-soluble zinc(II) phthalocyanines, which are decorated with four or eight umbelliferone moieties for photodynamic therapy (PDT). These compounds are linked peripherally to zinc(II) phthalocyanine by a triethylene glycol linker attached to pyridines, leading to cationic pyridinium units, able to increase the water solubility of the system. Beside their photophysical properties they were analyzed concerning their cellular distribution in human hepatocyte carcinoma (HepG2) cells as well as their phototoxicity towards HepG2 cells, Gram-positive (S.

Reversible Self-Assembly of Gold Nanoparticles Based on Co-Functionalization with Zwitterionic and Cationic Binding Motifs*.

We report a pH- and temperature-controlled reversible self-assembly of Au-nanoparticles (AuNPs) in water, based on their surface modification with cationic guanidiniocarbonyl pyrrole (GCP) and zwitterionic guanidiniocarbonyl pyrrole carboxylate (GCPZ) binding motifs. When both binding motifs are installed in a carefully balanced ratio, the resulting functionalized AuNPs self-assemble at pH 1, pH 7 and pH 13, whereas they disassemble at pH 3 and pH 11. Further disassembly can be achieved at elevated temperatures at pH 1 and pH 13.

Bridged Aromatic Oxo- and Thioethers with Intense Emission in Solution and the Solid State.

In this contribution, we report on a class of emitters based on bridged oxo- and/or thioethers revealing striking photoluminescence properties in fluid solution and in the solid state. In total, nine compounds were investigated concerning their photophysical properties, which were interpreted by quantum chemical calculations. To our delight, we discovered compounds possessing nearly identical photoluminescence quantum yields (Φ ) in solution and in the solid state, which has been rarely reported so far.

Take your Positions and Shine: Effects of Positioning Aggregation-Induced Emission Luminophores within Sequence-Defined Macromolecules.

A luminophore with aggregation-induced emission (AIE) is employed for the conjugation onto supramolecular ligands to allow for detection of ligand binding. Supramolecular ligands are based on the combination of sequence-defined oligo(amidoamine) scaffolds and guanidiniocarbonyl-pyrrole (GCP) as binding motif. We hypothesize that AIE properties are strongly affected by positioning of the luminophore within the ligand scaffold.

Prospects of ultraviolet resonance Raman spectroscopy in supramolecular chemistry on proteins.

Ultraviolet resonance Raman scattering (UVRR) has been frequently used for studying peptide and protein structure and dynamics, while applications in supramolecular chemistry are quite rare. Since UVRR offers the additional advantages of chromophore selectivity and high sensitivity compared with conventional non-resonant Raman scattering, it is ideally suited for label-free probing of relatively small artificial/supramolecular ligands exhibiting electronic resonances in the UV. In this perspective article, we first summarize results of UVRR spectroscopy in supramolecular chemistry in the context of peptide/protein recognition.

PEGylated sequence-controlled macromolecules using supramolecular binding to target the Taspase1/Importin α interaction.

A novel strategy to inhibit the oncologically relevant protease Taspase1 is explored by developing PEGylated macromolecular ligands presenting the supramolecular binding motif guanidiniocarbonylpyrrole (GCP). Taspase1 requires interaction of its nuclear localization signal (NLS) with import receptor Importin α. We show the synthesis and effective interference of PEGylated multivalent macromolecular ligands with Taspase1-Importin α-complex formation.

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding.

The first example of halogen-bonded fluorescent liquid crystals based on the interaction of iodofluorobenzene derivatives with nitro-cyanostilbenes is reported. The systematic variation of the fluorination degree and pattern indicates the relevance of the halogen bond strength for the induction of liquid crystalline properties. The modular self-assembly approach enables the efficient tuning of the fluorescence behaviour and mesomorphic properties of the assemblies.

All in One: Stimuli-Responsive, Efficient Mitotracking, and Single Source White Light Emission.

"All in one" type luminogens, possessing combined properties related to optical, materials, and biological implications, are of urgent demand today, mainly because of the combined application potential of such probes. To the best of our knowledge, until now, an "all in one" type white light emitter together with stimuli-responsive behavior and highly efficient mitochondrial-tracking ability has not been reported yet. In this contribution, for the first time, we have investigated a pair of luminogens exhibiting white light emission (CIE coordinates: 0.

Ultraviolet resonance Raman spectroscopy with a continuously tunable picosecond laser: Application to the supramolecular ligand guanidiniocarbonyl pyrrole (GCP).

We present a UVRR spectroscopy setup which is equipped with a picosecond pulsed laser excitation source continuously tunable in the 210-2600 nm wavelength range. This laser source is based on a three-stage optical parametric amplifier (OPA) pumped by a bandwidth-compressed second harmonic output of an amplified Yb:KGW laser. It provides <15 cm linewidth pulses below 270 nm, which is sufficient for resolving Raman lines of samples in condensed phase studies.