Design and Synthesis of Heterobimetallic Ru(II)–Ln(III) Complexes as Chemodosimetric Ensembles for the Detection of Biogenic Amine Odorants

The detection of neutral biogenic amines plays a crucial role in food safety. Three new heterobimetallic Ru­(II)–Ln­(III) donor-acceptor complexes, KPrRu, KNdRu, and KSmRu, K­{[Ru^(II)(^tBubpy)­(CN)₄]₂–Ln^(III)(H₂O)₄} (where ^tBubpy = 4,4′-di-<i>tert</i>-butyl-2,2′-bipyridine), have been synthesized and characterized. Their photophysical and X-ray crystallographic data were reported in this study. These complexes were found to be selective for biogenic amine vapors, such as histamine, putrescine, and spermidine, with a detection limit down to the ppb level. The sensitivities of these complexes to the amines were recorded as ∼log <i>K</i> = 3.6–5.0. Submicron rods of the complexes, with a nanoscale diameter and microscale length, were obtained through a simple precipitation process. Free-standing polymeric films with different degrees of porosity were fabricated by blending the submicron rods with polystyrene polymer. The polymer with the highest level of porosity exhibited the strongest luminescence enhancement after amine exposure. Real time monitoring of gaseous biogenic amines was applied to real fish samples (Atlantic mackerel) by studying the spectrofluorimetric responses of the Ru­(II)–Ln­(III) blended polymer film

Facet-Selective Growth of Organic Heterostructured Architectures via Sequential Crystallization of Structurally Complementary π‑Conjugated Molecules

In contrast to those for their polymeric counterparts, the controlled construction of organic heterostructured architectures derived from π-conjugated organic molecules has been rare and remains a great challenge. Herein, we develop a simple single-step solution strategy for the realization of organic heterostructures comprising coronene and perylene. Under a sequential crystallization process, an efficient doping step for coronene and perylene domains enables their perfect lattice matching, which facilitates facet-selective epitaxial growth of perylene domains on both the tips and the side surfaces of the preformed seed microwires by manipulating the growth pathways of the two pairs of materials. The present synthetic route provides a promising platform to investigate the detailed formation mechanism of complex organic heterostructures with specific topological configurations, further directing the construction of more functional heterostructured materials

Symmetrically Backfolded Molecules Emulating the Self-Similar Features of Sierpinski Triangle

<p>Novel branching motif in hierarchical self-similar molecules: we present an under-explored class of molecules featuring striking geometric resemblance to the famous fractal of Sierpinski triangle. Unlike the more traditional, starburst dendrimers, the centripetal-shaped Sierpinski molecules feature side branches symmetrically bent away from the growth direction of the main branch, thus contrasting the natural-tree shape. Molecule G3 exhibits three distinct levels of structural hierachy comprising the primary, secondary and tertiary branches, while the smaller G2 contains only features of the 1^st and 2^nd orders. In spite of the much larger conjugated backbone of G3, its UV-vis absorption remains little shifted in wavelength compared to G2, while the emission of G3 is curiously blue-shifted by over 50 nm from that of G2.</p

New Terthiophene-Conjugated Porphyrin Donors for Highly Efficient Organic Solar Cells

To mimic the natural photosynthetic systems utilizing chlorophylls to absorb light and store light energy, two new porphyrin-based small molecules of PTTR and PTTCNR have been developed for photovoltaic applications. The highest power conversion efficiency of 8.21% is achieved, corresponding to a short-circuit current of 14.30 mA cm^–2, open-circuit voltage of 0.82 V, and fill factor of 70.01%. The excellent device performances can be ascribed to the engineering of molecule structure and film morphology. The horizontal conjugation of 3,3″-dihexyl-terthiophene to porphyrin-core with the vertical aliphatic 2-octylundecyl peripheral substitutions, can not only effectively increase the solar flux coverage between the conventional Soret and Q bands of porphyrin unit, but also optimize molecular packing through polymorphism associated with side-chains and the linear π-conjugated backbones. And the additive of 1,8-diiodooctane and subsequent chloroform solvent vapor annealing facilitate the formation of the blend films with [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) characteristics of bicontinuous, interpenetrating networks required for efficient charge separation and transportation

Chromophoric Dyads for the Light-Driven Generation of Hydrogen: Investigation of Factors in the Design of Multicomponent Photosensitizers for Proton Reduction

Two new dyads have been synthesized and studied as photosensitizers for the light-driven generation of H₂ from aqueous protons. One of the dyads, <b>Dy-1</b>, consists of a strongly absorbing Bodipy (dipyrromethene-BF₂) dye and a platinum diimine benzenedithiolate (bdt) charge transfer (CT) chromophore, denoted as PtN₂S₂. The two components are connected through an amide linkage on the bdt side of the PtN₂S₂ complex. The second dyad, <b>Dy-2</b>, contains a diketopyrrolopyrrole dye that is linked directly to the acetylide ligands of a Pt diimine bis­(arylacetylide) CT chromophore. The two dyads, as well as the Pt diimine bis­(arylacetylide) CT chromophore, were attached to platinized TiO₂ via phosphonate groups on the diimine through sonication of the corresponding esters, and each system was examined for photosensitizer effectiveness in photochemical generation of H₂ from aqueous protons and electrons supplied by ascorbic acid. Of the three photosensitizers, <b>Dy-1</b> is the most active under 530 nm radiation with an initial turnover frequency of 260 h^–1 and a total of 6770 turnovers over 60 h of irradiation. When a “white” LED light source is used, samples with <b>Dy-2</b> and the Pt diimine bis­(arylacetylide) chromophore, while not as effective as <b>Dy-1</b>, perform relatively better. A key conclusion is that the presence of a strongly absorbing organic dye increases dyad photosensitizer effectiveness only if the energy of the CT excited state lies below that of the organic dye’s lowest excited state; if not, the organic dye does not improve the effectiveness of the CT chromophore for promoting electron transfer and the light-driven generation of H₂. The nature of the spacer between the organic dye and the charge transfer chromophore also plays a role in the effectiveness of using dyads to improve light-driven energy-storing reactions

From Mononuclear to Dinuclear Iridium(III) Complex: Effective Tuning of the Optoelectronic Characteristics for Organic Light-Emitting Diodes

Phosphorescent dinuclear iridium­(III) complexes that can show high luminescent efficiencies and good electroluminescent abilities are very rare. In this paper, highly phosphorescent 2-phenylpyrimidine-based dinuclear iridium­(III) complexes have been synthesized and fully characterized. Significant differences of the photophysical and electrochemical properties between the mono- and dinuclear complexes are observed. The theoretical calculation results show that the dinuclear complexes adopt a unique molecular orbital spatial distribution pattern, which plays the key role of determining their photophysical and electrochemical properties. More importantly, the solution-processed organic light-emitting diode (OLED) based on the new dinuclear iridium­(III) complex achieves a peak external quantum efficiency (η_ext) of 14.4%, which is the highest η_ext for OLEDs using dinuclear iridium­(III) complexes as emitters. Besides, the efficiencies of the OLED based on the dinuclear iridium­(III) complex are much higher that those of the OLED based on the corresponding mononuclear iridium­(III) complex

Significant Improvement of Dye-Sensitized Solar Cell Performance Using Simple Phenothiazine-Based Dyes

A series of simple phenothiazine-based dyes have been synthesized, in which a cyanoacrylate acceptor directly attached to the C(3) position of phenothiazine, and an additional linear electron-rich (4-hexyloxy)­phenyl group at C(7) on the opposite side of the acceptor, and an alkyl chain with different length at N(10) of the phenothiazine periphery are presented. The dye molecules have a linear shape which is favorable for the formation of a compact dye layer on the TiO₂ surface, while their butterfly conformations can sufficiently inhibit molecular aggregation. Moreover, the structural features of (4-hexyloxy)­phenyl donor moiety at the C(7) position of phenothiazine extends the π-conjugation of the chromophore, thus enhancing the performance of dye-sensitized solar cells (DSSCs). Moreover, the alkyl substituents with different chain length at the N(10) atom of phenothiazine could further optimize the performance through completely shielding the surface of TiO₂ from the I^–/I^3‑ electrolyte and subsequently reducing the leakage of dark current. Under simulated AM 1.5G irradiation, the PT-C6 based DSSC produces a short-circuit photocurrent of 15.32 mA cm^–2, an open-circuit photovoltage of 0.78 V, a fill factor of 0.69, corresponding to a power conversion efficiency (PCE) of 8.18%, which exceeds the reference N719 (7.73%) under identical fabrication conditions. Notably, the designed molecular structure represents the highest photovoltaic conversion efficiency value when compared with other reported phenothiazine-derived dyes

Achieving High-Performance Solution-Processed Orange OLEDs with the Phosphorescent Cyclometalated Trinuclear Pt(II) Complex

Cyclometalated Pt­(II) complexes can show intense phosphorescence at room temperature. Their emission properties are determined by both the organic ligand and the metal center. Whereas most of the related studies focus on tuning the properties by designing different types of organic ligands, only several reports investigate the key role played by the metal center. To address this issue, phosphorescent Pt­(II) complexes with one, two, and three Pt­(II) centers are designed and synthesized. With more Pt­(II) centers, the cyclometalated multinuclear Pt­(II) complexes display red-shifted emissions with increased photoluminescence quantum yields. Most importantly, solution-processed organic light-emitting diodes (OLEDs) with the conventional device structure using the multinuclear Pt­(II) complexes as emitters show excellent performance. The controlled device based on the conventional mononuclear Pt­(II) complex shows a peak external quantum efficiency, current efficiency, and power efficiency of 6.4%, 14.4 cd A^–1, and 12.1 lm W^–1, respectively. The efficiencies are dramatically improved to 10.5%, 21.4 cd A^–1, and 12.9 lm W^–1 for the OLED based on the dinuclear Pt­(II) complex and to 17.0%, 35.4 cd A^–1, and 27.2 lm W^–1 for the OLED based on the trinuclear Pt­(II) complex, respectively. To the best of our knowledge, these efficiencies are among the highest ever reported for the multinuclear Pt­(II) complex-based OLEDs

Heterometallic Cerium(IV) Perrhenate, Permanganate, and Molybdate Complexes Supported by the Imidodiphosphinate Ligand [N(<i>i</i>‑Pr₂PO)₂]⁻

Heterometallic cerium­(IV) perrhenate, permanganate, and molybdate complexes containing the imidodiphosphinate ligand [N­(<i>i</i>-Pr₂­PO)₂]⁻ have been synthesized, and their reactivity was investigated. Treatment of Ce­[N­(<i>i</i>-Pr₂­PO)₂]₃Cl (<b>1</b>) with AgMO₄ (M = Re, Mn) afforded Ce­[N­(<i>i</i>-Pr₂­PO)₂]₃­(ReO₄) (<b>2</b>) or Ce₂[N­(<i>i</i>-Pr₂­PO)₂]₆­(MnO₄)₂ (<b>3</b>). In the solid state, <b>3</b> is composed of a [Ce₂{N­(<i>i</i>-Pr₂­PO)₂}₆­(MnO₄)]⁺ moiety featuring a weak Ce–OMn interaction [Ce–OMn distance = 2.528(8) Å] and a noncoordinating MnO₄^– counteranion. While <b>3</b> is stable in the solid state and acetonitrile solution, it decomposes readily in other organic solvents, such as CH₂Cl₂. <b>3</b> can oxidize ethylbenzene to acetophenone at room temperature. Treatment of <b>1</b> with AgBF₄, followed by reaction with [<i>n</i>-Bu₄N]₂­[MoO₄], afforded [Ce­{N­(<i>i</i>-Pr₂­PO)₂}₃]₂­(μ-MoO₄) (<b>4</b>). Reaction of <i>trans</i>-Ce­[N­(<i>i</i>-Pr₂­PO)₂]₂­(NO₃)₂ (<b>5</b>), which was prepared from (NH₄)₂­Ce­(NO₃)₆ and K­[N­(<i>i</i>-Pr₂­PO)₂], with 2 equiv of [<i>n</i>-Bu₄N]­[Cp*­MoO₃] yielded <i>trans</i>-Ce­[N­(<i>i</i>-Pr₂­PO)₂]₂­(Cp*­MoO₃)₂ (<b>6</b>). <b>4</b> can catalyze the oxidation of methyl phenyl sulfide with <i>tert</i>-butyl hydroperoxide with high selectivity. The crystal structures of complexes <b>3</b>–<b>6</b> have been determined

Highly Selective Mitochondria-Targeting Amphiphilic Silicon(IV) Phthalocyanines with Axially Ligated Rhodamine B for Photodynamic Therapy

Two axially ligated rhodamine–Si­(IV)–phthalocyanine (Rh-SiPc) conjugates, bearing one and two rhodamine B, were synthesized and their linear and two-photon photophysical, subcellular localization and photocytotoxic properties were studied. These Rh-SiPc conjugates exhibited an almost exclusive mitochondrial localizing property in human nasopharyngeal carcinoma (HK-1) cells and human cervical carcinoma (HeLa) cells. Strong photocytotoxic but low dark cytotoxic properties were also observed for the two Rh-SiPc conjugates toward the HK-1 cells. Using nuclei staining method and flow cytometric DNA content analysis, apoptotic cell death was induced by these conjugates upon photoactivation. This observation is consistent with their mitochondrial localization property. The observed properties of these conjugates qualify them as promising PDT agents