Novel solid-state emissive polymers and polymeric blends from a T-Shaped benzodifuran scaffold: A comparative study

Two novel polyimines were synthesized from a benzodifuran based diamino monomer and two dialdehydes bearing bulky groups and a flexible spacer. The polymers display tuned luminescence performance according to the presence of half-salen groups. The effect of the intramolecular bond on the emission properties were examined. Two model compounds, replicating the same emissive Schiff base cores, were synthetized. From the models, dye-doped blends in the fluorophore/matrix ratio, resembling the polymers, were produced. Amorphous thin films of the covalent polymers and the polymeric blends were obtained by spin-coating technique. The Photoluminescent (PL) response of the different macromolecular systems were qualitatively and quantitatively examined and compared

Zinc (Ii) and aiegens: The “clip approach” for a novel fluorophore family. a review

Aggregation-induced emission (AIE) compounds display a photophysical phenomenon in which the aggregate state exhibits stronger emission than the isolated units. The common term of “AIEgens” was coined to describe compounds undergoing the AIE effect. Due to the recent interest in AIEgens, the search for novel hybrid organic–inorganic compounds with unique luminescence properties in the aggregate phase is a relevant goal. In this perspective, the abundant, inexpensive, and nontoxic d10 zinc cation offers unique opportunities for building AIE active fluorophores, sensing probes, and bioimaging tools. Considering the novelty of the topic, relevant examples collected in the last 5 years (2016–2021) through scientific production can be considered fully representative of the state-of-the-art. Starting from the simple phenomenological approach and considering different typological and chemical units and structures, we focused on zinc-based AIEgens offering synthetic novelty, research completeness, and relevant applications. A special section was devoted to Zn(II)-based AIEgens for living cell imaging as the novel technological frontier in biology and medicine

The role of zinc(II) ion in fluorescence tuning of tridentate pincers: A review

Tridentate ligands are simple low-cost pincers, easy to synthetize, and able to guarantee stability to the derived complexes. On the other hand, due to its unique mix of structural and optical properties, zinc(II) ion is an excellent candidate to modulate the emission pattern as desired. The present work is an overview of selected articles about zinc(II) complexes showing a tuned fluorescence response with respect to their tridentate ligands. A classification of the tridentate pincers was carried out according to the binding donor atom groups, specifically nitrogen, oxygen, and sulfur donor atoms, and depending on the structure obtained upon coordination. Fluorescence properties of the ligands and the related complexes were compared and discussed both in solution and in the solid state, keeping an eye on possible applications

A novel DR/NIR T-shaped aiegen: Synthesis and x-ray crystal structure study

We developed a new benzodifuran derivative as the condensation product between 2,6-diamino-4-(4-nitrophenyl)benzo[1,2-b:4,5-b’]difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane π-stacked in a columnar arrangement

Stimuli-responsive zinc (Ii) coordination polymers: A novel platform for supramolecular chromic smart tools

The unique role of the zinc (II) cation prompted us to cut a cross-section of the large and complex topic of the stimuli-responsive coordination polymers (CPs). Due to its flexible coordination environment and geometries, easiness of coordination–decoordination equilibria, “optically innocent” ability to “clip” the ligands in emissive architectures, non-toxicity and sustainability, the zinc (II) cation is a good candidate for building supramolecular smart tools. The review summarizes the recent achievements of zinc-based CPs as stimuli-responsive materials able to provide a chromic response. An overview of the past five years has been organised, encompassing 1, 2 and 3D responsive zinc-based CPs; specifically zinc-based metallorganic frameworks and zinc-based nanosized polymeric probes. The most relevant examples were collected following a consequential and progressive approach, referring to the structure–responsiveness relationship, the sensing mechanisms, the analytes and/or parameters detected. Finally, applications of highly bioengineered Zn-CPs for advanced imaging technique have been discussed

A highly water-soluble fluorescent and colorimetric pH probe

A new 5-(4-((2-(benzothiazole-2-carbonyl)hydrazono)methyl)-3-hydroxyphenoxy)N,N,N-trimethylpentan-1-aminium bromide (BTABr) fluorescent and colorimetric pH probe was easily synthesized by the condensation reaction of benzothiazole-2-carbohydrazide with 5-(4-formyl-3-hydroxyphenoxy)-N,N,N-trimethylpentan-1-aminium bromide. The benzothiazole moiety provided the emissive part of the molecule and the charged trimethyl amino group guaranteed outstanding solubility in water, for an organic molecule. pH titration experiments indicated that the probe is useful for monitoring acidic and alkaline solutions, turning reversibly in color/fluorescence just at a neutral pH value. Naked-eye colorimetric response was observed both in solution and in the solid state. In addition, the probe showed high stability and selectivity and large Stokes shifts. Because of these features, BTABr can potentially work as an on-off real-time pH sensor for intracellular pH imaging. The crystal structure of BTABr examined by single-crystal analysis showed a planar geometry of the molecule and confirmed the presence of a molecular stacking between molecules joined in a complex tridimensional hydrogen bonding pattern

A comparative study on low-temperature sol-gel ga-doped zinc oxide inverted PSCs

A low-temperature sol-gel Ga-doped ZnO (ZnO:Ga) thin film as the electron transport layer (ETL) for high efficiency inverted polymer solar cells (PSCs) has been realised. The ZnO:Ga precursor was prepared by dissolving zinc acetate and ethanolamine in the 2-methoxyethanol with Ga(NO3)3 at different concentration. Doped ZnO thin films were deposed on indium tin oxide (ITO)/glass substrates by spin-coating technique and the films annealed at 150°C for 5 minutes in air. To check performances of ZnO:Ga thin film were realized inverted polymer solar cells with the configuration ITO/ZnO:Ga/photoactive layer/MoO3/Ag. The photoactive layer was a blend of poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b′)dithiophene)-2,6-diyl-alt-(4-(2-octanoyl)-3-fluorothieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-CF) and [6,6]-phenyl C71 butyric acid methyl ester ([70]PCBM) (1:1.5 w/w). In this work was investigated the effect of gallium concentration on the photovoltaic behavior of PSCs. The best efficiency of 7.7% was reached by using a 6 at% ZnO:Ga film as ETL

AIEgen orthopalladated hybrid polymers for efficient inactivation of the total coliforms in urban wastewater

Monitorable AIE polymers with a bioactive pattern are employed in advanced biomedical applications such as functional coatings, theranostic probes, and implants. After the global COVID-19 pandemic, interest in developing surfaces with superior antimicrobial, antiproliferative, and antiviral activities dramatically increased. Many formulations for biocide surfaces are based on hybrid organic/inorganic materials. Palladium (II) complexes display relevant activity against common bacteria, even higher when compared to their uncoordinated ligands. This article reports the design and synthesis of two series of orthopalladated polymers obtained by grafting a cyclopalladated fragment on two diferent O, N chelating Schif base polymers. Diferent grafting percentages were examined and compared for each organic polymer. The fuorescence emission in the solid state was explored on organic matrixes and grafted polymers. DFT analysis provided a rationale for the role of the coordination core. The antibacterial response of the two series of hybrid polymers was tested against the total coliform group of untreated urban wastewater, revealing excellent inactivation abilit

A novel l-shaped fluorescent probe for aie sensing of zinc (Ii) ion by a dr/nir response

In the field of optical sensors, small molecules responsive to metal cations are of current interest. Probes displaying aggregation-induced emission (AIE) can solve the problems due to the aggregation-caused quenching (ACQ) molecules, scarcely emissive as aggregates in aqueous media and in tissues. The addition of a metal cation to an AIE ligand dissolved in solution can cause a “turn-on” of the fluorescence emission. Half-cruciform-shaped molecules can be a winning strategy to build specific AIE probes. Herein, we report the synthesis and characterization of a novel L-shaped fluorophore containing a benzofuran core condensed with 3-hydroxy-2-naphthaldehyde crossed with a nitrobenzene moiety. The novel AIE probe produces a fast colorimetric and fluorescence response toward zinc (II) in both in neutral and basic conditions. Acting as a tridentate ligand, it produces a complex with enhanced and red-shifted emission in the DR/NIR spectral range. The AIE nature of both compounds was examined on the basis of X-ray crystallography and DFT analysis

Thermo-Induced Fluorochromism in Two AIE Zinc Complexes: A Deep Insight into the Structure-Property Relationship

Solid-state emitters exhibiting mechano-fluorochromic or thermo-fluorochromic responses represent the foundation of smart tools for novel technological applications. Among fluo-rochromic (FC) materials, solid-state emissive coordination complexes offer a variety of fluorescence responses related to the dynamic of noncovalent metal-ligand coordination bonds. Relevant FC behaviour can result from the targeted choice of metal cation and ligands. Herein, we report the synthesis and characterization of two different colour emitters consisting of zinc complexes obtained from N,O bidentate ligands with different electron-withdrawing substituents. The two complexes are blue and orange solid-state fluorophores, respectively, highly responsive to thermal and me-chanical stress. These emitters show a very different photoluminescent (PL) pattern as recorded before and after the annealing treatment. Through X-ray structural analysis combined with thermal analysis, infrared (IR) spectroscopy, PL, and DFT simulation we provide a comprehensive analysis of the structural feature involved in the fluorochromic response. Notably, we were able to correlate the on-off thermo-fluorochromism of the complexes with the structural rearrangement at the zinc coordination core