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2,1,3-Benzothiadiazole (BT) and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes, organic solar cells and organic field-effect transistors. Due to their strong electron-withdrawing ability, construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials. In this contribution, we review the synthesis of various polymers, small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes. Furthermore, the molecular design rules based on these cores are discussed.

Inspired by the flexibility of the bottom-up approach in choosing building blocks of two-dimensional (2D) materials, a π-conjugated metal complex nanosheet (HHTP-Cu) was successfully prepared by the coordination of the ligand 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and Cu(II) ion at the water/oil interface. Field-emission scanning electron microscopy disclosed the large-size domain and transmission electron microscopy revealed the sheet morphology of the nanosheet. The flat and smooth surface was also confirmed by atomic force microscopy which further demonstrated the proposed structure. Energy dispersive X-ray spectroscopy was applied to verify the homogeneous distribution of the elements while X-ray photoelectron spectroscopy was used to investigate the composition of the nanosheet.

A terpyridine-substituted cyanostilbene derivative ( Z )-2-(4 ¢ -([2,2 ¢ :6 ¢ ,2 ² -terpyridin]-4 ¢ -yl)-[1,1 ¢ -biphenyl]-4-yl)-3-phenylacrylonitrile ( CNSTPy ) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission (ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ~1.5 mJ cm−2. The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.

As we all know, organic phosphorus compounds have high application values in chemical industries. Compared with traditional compounds with P-X (X = Cl, Br, I) and P-H bonds, phosphorylation reagents containing P(O)-OH bonds are stable, environmentally friendly, and inexpensive. However, in recent years, there have been few studies on the selective functionalization of P(O)-OH bonds for the fabrication of P-C and P-Z bonds. In general, four-coordinated P(O)-OH compounds have reached coordination saturation due to the phosphorus atom center, but cannot evolve the phosphorus coordination center through intra-molecular tautomerization; however, the weak coordination effects between the P=O bond and transition metals can be utilized to activate P(O)-OH bonds. This review highlights the most important recent contributions toward the selective functionalization of P(O)-OH bonds via cyclization/cross coupling/esterification reactions using transition metals or small organic molecules as the catalyst.

Patterning of L10 FePt nanoparticles (NPs) with high coercivity offers a promising route to develop bit-patterned media (BPM) for the next generation magnetic data recording system, but the synthesis of monodisperse FePt NPs and mass production of their nanopatterns has been a long-standing challenge. Here, highly efficient nanoimprint lithography was applied for large-scale universal patterning, which was achieved by imprinting the solution of a single-source bimetallic precursor. The rigid coplanar metallic cores and the surrounding flexible tails in the bimetallic complex permit the spontaneous molecular arrangements to form the highly ordered negative morphology replicated from the soft template. In-situ pyrolysis study was then investigated by one-pot pyrolysis of the precursor under an Ar/H2 atmosphere, and the resultant NPs were fully characterized to identify the phase, morphology and magnetic properties. Finally, highly-ordered patterns on certain substrates were preserved perfectly after pyrolysis and could be potentially utilized in magnetic data recording media.

We prove the pointwise decay of solutions to three linear equations: (i) the transport equation in phase space generalizing the classical Vlasov equation, (ii) the linear Schrodinger equation, (iii) the Airy (linear KdV) equation. The usual proofs use explicit representation formulae, and either obtain $L^1$---$L^\infty$ decay through directly estimating the fundamental solution in physical space, or by studying oscillatory integrals coming from the representation in Fourier space. Our proof instead combines "vector field" commutators that capture the inherent symmetries of the relevant equations with conservation laws for mass and energy to get space-time weighted energy estimates. Combined with a simple version of Sobolev's inequality this gives pointwise decay as desired. In the case of the Vlasov and Schrodinger equations we can recover sharp pointwise decay; in the Schrodinger case we also show how to obtain local energy decay as well as Strichartz-type estimates. For the Airy equation we obtain a local energy decay that is almost sharp from the scaling point of view, but nonetheless misses the classical estimates by a gap. This work is inspired by the work of Klainerman on $L^2$---$L^\infty$ decay of wave equations, as well as the recent work of Fajman, Joudioux, and Smulevici on decay of mass distributions for the relativistic Vlasov equation., Comment: 16 pages; expository with some (hopefully) new material. v2: fixed typos in the Strichartz exponent, sharpened interpolation to remove epsilon loss, updated reference list. v4: added Remark 23 showing how to recover standard L^1-L^\infty decay estimates from the weighted L^2-L^\infty argument for Schrodinger

A series of neutral luminescent tetranuclear and mononuclear copper(I) halide complexes, [Cu4I4(dpna)4] (1) and [CuX(dpna)2] dpna = 1-(diphenylphosphino)naphthalene, X = Br (2), Cl (3), were synthesized, and their molecular structures and photophysical properties were investigated. Complex 1 has a cubane-like structure with four Cu atoms pseudo-tetrahedral and four I atoms serving as μ3-bridges. The coordination geometry of the copper centers in 2–3 are trigonal-planar. In the solid state, complexes 1–3 display blue photoluminescence (λmax = 423–463 nm) at 298 K. The emission of the complexes originate from the (σ+X)→π* transition. All three complexes displayed good thermal stability.

Reduced graphene oxide containing Fe3O4 nanoparticles was decorated with hydroxypropyl-β-cyclodextrin (HP-β-CD) to construct a novel nanocomposite (3D-rGO/Fe3O4/HP-β-CD). The composite was placed on a glassy carbon electrode (GCE) to design an electrochemical sensor for detecting simultaneously serotonin (5-HT), dopamine (DA), and ascorbic acid (AA). The interconnected porous reduced graphene oxide framework tightly anchored to the Fe3O4 magnetic nanoparticles warrants good electrical conductivity and efficient catalytic activity. The HP-β-CD acts as a supramolecular host with high recognition ability for 5-HT, DA and AA. Well-separated oxidation peaks and increased peak currents were observed for 5-HT, DA, and AA individually and in mixtures by differential pulse voltammetry (DPV). The following figures of merit were found for simultaneous electrochemical determination of 5-HT, DA, and AA: (a) Well separated peaks at around 0.316, 0.16 and − 0.044 V; (b) linear responses in the 0.01 – 25 μM, 0.02 – 25 μM and 10 – 350 μM; (c) detection limits of 3.3 nM, 6.7 nM and 3.3 μM (S/N = 3), and (d) recoveries of 96.9-103%, 97.3%-102% and 96.3-105% from spiked serum samples, respectively. All relative standard deviation (RSD) are less than 4%.

Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (1H, 13C and 31P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh3, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S1 → S0) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts.

The chemical reactivity of ferrocenylethynylpyridine ligand with some metal complexes has been studied. Ligation of this ferrocenyl-functionalized pyridyl metalloligand with triosmium carbonyl cluster [Os3(CO)10(NCMe)2] via oxidative addition led to a new supramolecular heterobimetallic cluster [Os3(CO)10(μ-H){μ-NC5H3C≡C(η5-C5H4)Fe(η5-C5H5)}] 1 in good yield. Coordination of Co2(CO)8 with the alkyne functionality of 1 gave another new heterotrimetallic cluster complex [Os3(CO)10(μ-H){μ-NC5H3{C2Co2(CO)6}(η5-C5H4)Fe(η5-C5H5)}] 2 in which the molecule possesses a Co2C2 core adopting the pseudo-tetrahedral geometry having the alkyne bond lying perpendicular to the Co–Co vector. Characterization of 1 and 2 by IR and 1H NMR spectroscopies indicated that these complexes consist of an orthometalated trinuclear carbonyl cluster unit rigidly connected to a ferrocenyl unit. Electrochemical studies on 1 and 2 revealed that both of them undergo a reversible one-electron oxidation at iron followed by an irreversible oxidation of the Os3 cluster core. Another simple mononuclear zinc(II) complex [ZnCl2{(NC5H4C≡C(η5-C5H4)Fe(η5-C5H5)}2] 3 was also prepared for comparison of the electrochemical data with those of 1 and 2.

Four metallated conjugated oligothiophenes, S-1, S-2, S-3 and S-4, with platinum(II) aryleneethynylenes as the electron-rich building block were synthesized to investigate their physicochemical and photovoltaic properties. These small molecules possess fairly low-lying HOMO energy levels which match with the LUMO energy level of the electron acceptor PC70BM ([6,6]-phenyl-C71-butyric acid methyl ester). Using the simple process of spin-coating solution fabrication technique, S-1:PC70BM (1:4, w/w) based organic solar cells exhibiting a high V oc of 0.913 V, with a PCE value of 0.88% were developed. In contrast, the OSC device based on S-2:PC70BM (3:7, w/w) displayed a higher PCE of 1.59% with a higher J sc value of 5.89 mA cm−2. The device based on S-4:PC70BM (1:4, w/w) exhibited a PCE value of 1.56%, with a V oc of 0.917 V.

Two new solution-processible platinum(II) polyyne polymers P1 and P2 bridged by diketopyrrolopyrrole and isoindigo units have been synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum(II) chloride precursors and the corresponding diacetylene ligands. The photophysical and electrochemical properties of P1 and P2 were investigated. These metallo-organic polymers have relatively narrow bandgaps of around 1.58–1.70 eV and broad absorption bands which are favorable for harvesting solar energy.

This review focuses on the recent development in the rigid-rod metallopolymers of late transition metals based on triple-bond building blocks. The synthesis, structure-property relationships and potential applications of organometallic poly(arylene ethynylene)s will be discussed in detail. These functional metal-based polymers can exhibit intriguing optical, electronic and magnetic properties. Considerable focus is placed on the design strategies towards tuning the optical bandgap and emission color (spanning almost the whole visible spectrum) of this class of metallopolymers, and the investigation of their use as active materials for light/electrical energy conversion and energy and information storage. The ongoing scientific challenges and future prospects of this research field are also highlighted.

The use of various diethynylarene ligands in the synthesis of some metal carbonyl linking clusters is established. New dimeric complexes of osmium [{(μ-CO)Os3(CO)9}2(μ3-η2-diyne)], ruthenium [{(μ-H)Ru3(CO)9}2(μ3-η2,η2-diyne)] or [{(μ-CO)Ru3(CO)9}2(μ3-η2-diyne)] and cobalt [{Co2(CO)6}2(η2-diyne)] (diyne = HC≡CArC≡CH, Ar = 2,7-fluorene, 2,7-fluoren-9-one, bithiazole or bithiophene) have been prepared in good yields from the reaction of [Os3(CO)10(NCMe)2], [Ru3(CO)12] or [Ru3(CO)10(NCMe)2] and [Co2(CO)8] with half an equivalent of the appropriate diethynylarene ligand, respectively. All these cluster compounds have been characterized by IR and 1H NMR spectroscopies and mass spectrometry. The molecular structures of three of them have been determined by X-ray crystallography. For the group 8 osmium and ruthenium analogues, the hexanuclear carbonyl clusters consist of two trinuclear metal cores with the exhibition of the μ3-(η2-||) bonding mode for the acetylene groups when [M3(CO)10(NCMe)2] (M = Ru, Os) was used and the μ3-η2,η2 bonding mode when [Ru3(CO)12] served as the starting cluster. The tetracobalt species possesses two Co2C2 cores adopting the pseudo-tetrahedral geometry having the alkyne bond lying perpendicular to the Co–Co vector in each core. Density functional theory was also used to study the electronic structures of selected molecules.

In an influential 1964 article, P. Lax studied $2 \times 2$ genuinely nonlinear strictly hyperbolic PDE systems (in one spatial dimension). Using the method of Riemann invariants, he showed that a large set of smooth initial data lead to bounded solutions whose first spatial derivatives blow up in finite time, a phenomenon known as wave breaking. In the present article, we study the Cauchy problem for two classes of quasilinear wave equations in two spatial dimensions that are closely related to the systems studied by Lax. When the data have one-dimensional symmetry, Lax's methods can be applied to the wave equations to show that a large set of smooth initial data lead to wave breaking. Here we study solutions with initial data that are close, as measured by an appropriate Sobolev norm, to data belonging to a distinguished subset of Lax's data: the data corresponding to simple plane waves. Our main result is that under suitable relative smallness assumptions, the Lax-type wave breaking for simple plane waves is stable. The key point is that we allow the data perturbations to break the symmetry. Moreover, we give a detailed, constructive description of the asymptotic behavior of the solution all the way up to the first singularity, which is a shock driven by the intersection of null (characteristic) hyperplanes. We also outline how to extend our results to the compressible irrotational Euler equations. To derive our results, we use Christodoulou's framework for studying shock formation to treat a new solution regime in which wave dispersion is not present., Comment: This version is very close to the one that will soon be published. Based in part on the comments of referees, we have made the following changes: 1) Change of title; 2) We have provided additional context for our work in the text; 3) Addition of a few new references; 4) Corrections of typos and minor errors

In this paper, a novel white-light luminescent material derived from bis(8-hydroxyquinolinato)zinc(II), Zn(2DCDC-HCz-Q)2, was designed and synthesized, which is comprised of bis(8-hydroxyquinolinato)zinc (ZnQ2), 3-(dicyanomethylene)-5,5-dimethyl-cyclohexene (DCDC) and carbazole (Cz) groups serving as yellowish-green-, blue- and red-light emitting units, respectively. The luminescence properties of Zn(2DCDC-HCz-Q)2 were characterized and discussed. Zn(2DCDC-HCz-Q)2 showed remarkable white-light fluorescence, exhibiting CIE coordinates of around (0.32, 0.39) and coloration index of 77.7 %. During the emission process, ZnQ2 unit emits yellowish-green light by induction of the Cz group through Forster energy transfer, and red-light emission is realized by charge transfer from Cz ring to DCDC unit. Hence, Zn(2DCDC-HCz-Q)2 shows a great potential to be used in the fabrication of white-light organic light-emitting device.

A new series of organic/inorganic composite Langmuir–Blodgett (LB) films consisting of 2-aminofluorene (Fl–NH2) as the π-conjugated organic molecule, an europium-substituted polyoxometalate (POM, POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2], which are denoted by EuW10, EuW22 and EuW11, respectively) as the inorganic component, were prepared. Structural and photophysical characterization of these LB films were achieved by π–A isotherms, UV–Vis absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and surface photovoltage spectroscopy. Our experimental results indicate that stable Langmuir and LB films are formed in pure water and POM sub-phases. Luminescence spectra of the prepared hybrid LB films show that tunable emission color can be obtained due to the dual-emissive nature of the mixed Fl–NH2/POM blends. These 2-aminofluorene-based LB films displayed interesting electrical conductivity behavior. Among them, Fl–NH2/EuW11 3-layer films showed a good electrical response with the a tunneling current up to ± 100 nA when the voltage was monitored at −0.8 to 1.5 V. These LB composites show good photovoltage responses and a photovoltage of 2.7 μV can be obtained for the Fl–NH2/EuW22 system when it is excited by light.

3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.

Soluble, thermally stable, and easily processable platinum(II) polyyne polymers of the form trans-[–Pt(PBu3)2C≡CRC≡C–]n (R = 2,8-disubstituted dibenzothiophene, 2,8-disubstituted and 3,7-disubstituted dibenzothiophene-S,S-dioxide units) have been prepared in good yields by CuI-catalyzed polymerization involving the dehydrohalogenating coupling of trans-[PtCl2(PBu3)2] and HC≡CRC≡CH. We report their optical absorption and photoluminescence spectra and compare the results with the monomeric model complexes trans-[Pt(Ph)(PEt3)2C≡CRC≡CPt(Ph)(PEt3)2]. The different electronic properties and linkage geometry of the central R group lead to new organometallic materials with distinct photophysical traits. The polymer with more conjugated 3,7-disubstituted dibenzothiophene-S,S-dioxide mainly displays fluorescence band, while its isomer with less conjugated 2,8-disubstituted spacer effectively enhances the intersystem crossing rate and strong phosphorescence emission can be detected even at room temperature.

A new family of organometallic/inorganic hybrid Langmuir–Blodgett (LB) films, consisting of rigid-rod alkynylplatinum(II)–zinc(II) porphyrinate complex (OMA) as the π-conjugated donor–acceptor-type molecule, molybdophosphoric heteropolyacid and heteropolyacid salt (POM = H3PMo12O40, Na5IMo6O24, abbreviated as HPMo12 and NaIMo6, respectively) of the Keggin and Anderson structures as the inorganic composite, were prepared and characterized by π-A isotherms, UV–vis absorption and luminescence spectra, scanning tunneling microscopy and surface photovoltage spectroscopy. Our experimental results indicate that stable, well-defined and well-organized Langmuir and LB films have been formed in pure water and POM subphase. Luminescence spectra of these hybrid LB films show that HPMo12 can increase the emission intensity of OMA to some extent. These LB composites show good photovoltage responses and a photovoltage of 11.1 μV can be obtained for the OMA/HPMo12 system when it is excited by light. The 3-layer LB films on ITO wafer can also display intriguing electrical conductivity behavior and the tunneling current amounts to ±100 nA when the voltage is set at −0.7–2.5 and −1.3–0.8 V for OMA/HPMo12 and OMA/NaIMo6 hybrid LB films, respectively.

We report the synthesis of some heterobimetallic carbonyl clusters of groups 8 and 9 derived from diethynylsilane and diethynyldisilane ligands. The triosmium carbonyl clusters containing a pendant acetylene unit [(μ-CO)Os3(CO)9(μ3-η2-HC≡C-E-C≡CH)] [E = Si(CH3)2, Si(CH3)2–Si(CH3)2 and SiPh2] were prepared and subsequently used for mixed-metal cluster formation. New diyne complexes of the type [{(μ-CO)Os3(CO)9}{Co2(CO)6}(μ3-η2:η2-diyne)] and [{(μ-CO)Os3(CO)9}{(μ-H)Ru3(CO)9}(μ3-η2:μ3-η2, η2-diyne)] [diyne = HC≡CSi(CH3)2C≡CH, HC≡CSi(CH3)2–Si(CH3)2C≡CH or HC≡CSi(Ph)2C≡CH] have been prepared in good yields from the reaction of [(μ-CO)Os3(CO)9(μ3-η2-HC≡C-E-C≡CH)] with a molar equivalent of [Co2(CO)8] and [Ru3(CO)12], respectively. All the new heterobimetallic compounds have been characterized by IR and 1H NMR spectroscopy and mass spectrometry. The X-ray crystal structures and computational analyses based on density functional theory of these three molecules have been studied. Structurally, the dicobalt species adopts a pseudo-tetrahedral Co2C2 core with the alkyne bond which lies essentially perpendicular to the Co–Co vector. For the mixed osmium–ruthenium analogue, the hexanuclear carbonyl cluster consist of two trinuclear metal cores with the μ3-(η2-||) bonding mode for the acetylene group in the former case and the μ3-η2, η2 bonding mode in the latter one.

A new family of organometallic/inorganic composite Langmuir–Blodgett (LB) films consisting of the rigid-rod dinuclear gold(I) complex coordinated with 9,9-bis(4-ethynylphenyl)fluorene (denoted as Au-DPF) as the π-conjugated organometallic molecule coupled with some europium-substituted polyoxometalates (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component were prepared and characterized by π–A isotherms, UV–vis absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and surface photo-voltage spectroscopy. Luminescence spectra of the prepared hybrid LB films show that the near-white emission spectra can be obtained due to the dual-emissive nature of the mixed Au-DPF/POM blends, and POM can facilitate broad aggregate emission bands. These Au-diyne-based LB films displayed interesting electric conductivity behavior. Among them, Au-DPF/K13[Eu(SiW11O39)2] 13-layer film showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between −1.3 and 1.8 V. The photovoltage response of Au-DPF/EuW22 amounts to 1.5 μV.

Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer, poly(N-vinylcarbzole), and an electron-transporting auxiliary, 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene, codoped with two phosphorescent dyes: Iridium(III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2′) picolinate (FIrpic) and home-made Ir-G2 for blue and red emission, respectively. With the structure of ITO/PEDOT:PSS 4083(40 nm)/emission layer(80 nm)/Ba(4 nm)/Al(120 nm), the device showed a maximal luminous efficiency (LE) of 13.5 cd A−1(corresponding to an external quantum efficiency (EQE) of 6.8%), and a peak power efficiency (PE) of 6.5 lm W−1 at 6.0 V. Meanwhile, the device exhibited pure white emission with Commission Internationale de l’Eclairage (CIE) coordinates of (0.34, 0.35) at a current density of 12 mA cm−2, which is very close to the equi-energy white point with CIE coordinates of (0.33, 0.33). The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer (PEDOT:PSS) and incorporating poly[(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorenene)-alt-2,7-(9,9-dioctyfluorene)] (PFN) as an electron injection layer at the cathode. The optimized device showed an LE of 24.6 cd A−1 (with an EQE of 14.1%), while the peak power efficiency reached 12.66 lm W−1. Moreover, the WPLEDs showed good electroluminescence (EL) stability over a wide range of operating current density and luminance.

The synthesis, characterization and photophysics of a solution-processable metallopolyyne of platinum (P1) functionalized with the dioctyloxyphenyl-substituted thienopyrazine–thiophene hybrid spacer and its model molecular complex (M1) are described. Such metallopolymer P1 possesses a very low bandgap of 1.50 eV which extends towards the near-infrared (NIR) range of the solar spectrum, and represents one of the lowest optical bandgaps reported for metallopolyynes. With the capability of spanning a wider solar-radiation range, P1 can be used to fabricate efficient solar cells with power conversion efficiencies (PCEs) of up to 0.46% under air mass (AM1.5) simulated solar illumination. The electronic effect of the central heterocyclic ring sandwiched between the two thiophene units on the optical properties of these metallopolyynes has been investigated. The present study provides a good approach towards achieving conjugated polymeric materials with a broad solar absorption and demonstrates the potential of low-bandgap metallopolyynes for simultaneous visible and NIR light power generation.

The use of diethynylsilane, diethynyldisilane and diethynyldisiloxane in the synthesis of some linked metal carbonyl clusters is demonstrated. New dimeric η2-diyne complexes of cobalt [{Co2(CO)6}2(η2-diyne)], ruthenium [{(μ-H)Ru3(CO)9}2(μ3-η2,η2-diyne)] and osmium [{(μ-CO)Os3(CO)9}2(μ3-η2-diyne)] {diyne=HC≡CSi(CH3)2C≡CH, HC≡CSi(CH3)2–Si(CH3)2C≡CH, HC≡CSi(CH3)2–O–Si(CH3)2C≡CH or HC≡CSi(Ph)2C≡CH} have been prepared in good yields from the reaction of [Co2(CO)8], [Ru3(CO)12] and [Os3(CO)10(NCMe)2] with half an equivalent of the appropriate diyne ligand, respectively. All the twelve compounds have been characterized by IR and 1H NMR spectroscopies and mass spectrometry. The molecular structures of eight of them have been determined by X-ray crystallography. Structurally, each of the tetracobalt species displays two Co2C2 cores adopting the pseudo-tetrahedral geometry with the alkyne bond lying essentially perpendicular to the Co–Co vector. For the group 8 ruthenium and osmium analogues, the hexanuclear carbonyl clusters consist of two trinuclear metal cores with the μ3-η2,η2 bonding mode for the acetylene groups in the former case and μ3-(η2-||) bonding mode in the latter one. Density functional theory was employed to study the electronic structures of these molecules in terms of the nature of the silyl or disilyl unit and its substituents.

A new series of luminescent group 10–12 metal alkynyl complexes and polyyne polymer containing a central tris(p-ethynylphenyl)amine bridging chromophore were prepared. The regiochemical structures of these triangular-shaped trinuclear compounds and polymer were studied by various spectroscopic and photophysical analyses. Upon photoexcitation, each of them emits an intense purple-blue fluorescence emission in the near UV region in dilute fluid solutions at room temperature. Harvesting of organic triplet emissions observed in the low-energy region harnessed through the strong heavy-atom effects of group 10–12 transition metals was examined and the results were compared among these three neighboring late transition metal elements. The influence of group 15 nitrogen-based heteroatom on the intersystem crossing rate and the spatial extent of the lowest singlet and triplet excitons was fully elucidated and a comparison was made to the nearest group 14 and 16 neighbors in the same row of the Periodic Table.

A novel diblock copolymer with a polyrotaxane block α-cyclodextrins-poly (e-caprolactone)-b-poly{2,5-bis[(4-methoxypheny)oxycabony]-styrene} (α-CD-PCL-b-PMPCS) was successfully synthesized by combining ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The diblock copolymer was confirmed by 1H NMR, GPC and solid-state 13C CP/MAS NMR spectroscopic analysis. Its phase structures and phase transitions were investigated by thermogravimetric analyses and wide-angle X-ray diffraction (WAXD). WAXD and solid-state 13C CP/MAS NMR spectroscopic study confirmed that inclusion complexes domains of the polyrotaxanes assumed a channel-type structure.

The difurylphosphido-bridged dinuclear complex [Ru2(CO)6(μ-PFu2)(μ-η1,η2-Fu)] (Fu = 2-furyl) 1 readily reacts with two equivalents of each of the terminal alkynes HC≡CR (R = Fc, p-C6H4Fc, p-C6H4NO2, Fc = Fe(η5-C5H5)(η5-C5H4)) by an interesting head-to-tail ynyl coupling with a furan group to form a series of phosphido-bridged diruthenium compounds containing a novel furyl-substituted C4 hydrocarbyl chain of stoichiometry [Ru2(CO)4(μ-PFu2){μ-η1,η1,η2,η3-RCC(H)C(R)C(H)Fu}] (R = Fc 2, p-C6H4Fc 3, p-C6H4NO2 4) in moderate to good yields. Reaction of 1 with an equimolar amount of HC≡CFc and HC≡C(p-C6H4NO2) afforded a pair of isomers of [Ru2(CO)4(μ-PFu2){μ-η1,η1,η2,η3-R1CC(H)C(R2)C(H)Fu}] (R1 = Fc, R2 = p-C6H4NO2 5a; R1 = p-C6H4NO2, R2 = Fc 5b) together with a small mixture of 4. X-ray crystal structures of 2, 3, 5a and 5b are reported. All of these new alkyne-derived dinuclear complexes are electron precise with 34 cluster valence electrons in which the μ-η1,η2-furyl ligand acts as a three-electron donor and the μ-phosphido Ru2 framework is retained in the products upon alkyne coupling reactions. The resulting organic fragment of each complex is coordinated to the Ru atoms via a π, a π-allyl and two σ bonds, and donates seven electrons to the metal core.

A novel approach based on conjugation interruption was developed for a luminescent and thermally stable platinum(II) polyyne polymer trans-[–Pt(PBu3)2C≡C(C6H4)CH2(C6H4)C≡C–]n (1) containing the diphenylmethane chromophoric spacer. Particular attention was focused on the photophysical properties of this group 10 polymetallayne and comparison was made to its binuclear model complex trans-[Pt(Ph)(PEt3)2C≡C(C6H4)CH2(C6H4)C≡CPt(Ph)(PEt3)2] (2) and their closest group 11 gold(I) and group 12 mercury(II) neighbors, [MC≡C(C6H4)CH2(C6H4)C≡CM] (M = Au(PPh3) (3), HgMe (4)). The regiochemical structures of these angular-shaped compounds were studied by various spectroscopic analyses. Upon photoexcitation, each of them emits an intense purple-blue fluorescence emission in the near UV region in dilute fluid solutions at room temperature. Harvesting of organic triplet emissions harnessed through the strong heavy-atom effects of group 10–12 transition metals was examined. These metal-containing phenyleneethynylenes spaced by the conjugation-breaking CH2 unit were found to have high optical gaps and high-energy triplet states. The influence of metal and sp3-hybridized methylene conjugation-interrupters on the intersystem crossing rate and the spatial extent of the lowest singlet and triplet excitons was fully elucidated. Our investigations indicate that high-energy triplet states in these materials intrinsically give rise to very efficient phosphorescence with fast radiative decays.

Thermal reaction of [Ru2(CO)6(μ-PFu2)(μ-η1,η2-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh2) produces a novel diruthenium complex [Ru2(CO)5(μ-PFu2)(μ-η1,η1,η2-C14H8PPh2)] (1) in good yield whereas the corresponding reaction between [(μ-H)4Ru4(CO)12] and AnPPh2 gives [HRu(CO)3(PPh2C14H8)][(μ-H)4Ru4(CO)11(AnPPh2)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh2 functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru–C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru–Ru bonds, and the making of a Ru–P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.

This review briefly summarizes research work carried out by the author in the past decade on rigid-rod transition metal polyyne polymers and their molecular precursors. The research involves the synthesis, spectroscopic and photophysical characterization, ligand functionalization, and possible optoelectronic applications of transition metal polyyne polymers. Herein, oligomeric and polymeric metal alkynyl systems of the late transition metals are discussed, and particular attention is focused on the electronic absorption spectroscopy and photoluminescence behavior, thermal stability and structural aspects of these polymetallaynes. A detailed account of the evolution of the first excited singlet and triplet state on the electronic structure of the organic spacer groups of these metal polyyne polymers is also given and the interplaying factors that govern the spatial extent of the lowest-lying singlet and triplet energy levels for the chemical tailoring of the singlet–triplet gap are elucidated. The possible developments of this research are also envisaged.

A neutral triosmium alkylidyne carbonyl cluster containing the 4-vinylpyridine (4vpy) moiety [Os3(µ-H)2(CO)9(µ3-CNC5H4-CH=CH2)] (1) has been prepared as red crystalline solids in good yield. Monomer (1) was copolymerized with styrene in the presence of α,α'-azobis(isobutyronitrile) (AIBN) in chloroform at 60°C and a polymer-immobilized alkylidyne cluster of osmium was obtained. To compare the spectroscopic properties with the copolymers, a structurally similar repeating unit of the copolymers, [Os3(µ-H)2(CO)9(µ-3-CNC5H4-CH2CH3)I](2), has also been synthesized and characterized.

A new luminescent and thermally stable platinum(II) polyyne polymer trans-[–Pt(PBu3)2C≡CArC≡C–]n (P1) containing the 2,7-fluorene chromophoric spacer substituted by pendant carbazolyl group via long alkyl bridges. The regiochemical structures of these compounds were studied by various spectroscopic analyses. We report the photophysical properties of this group 10 polymetallayne and a comparison was made to its binuclear model complex trans-[Pt(Ph)(PEt3)2C≡CArC≡CPt(Ph)(PEt3)2] (M1) as well as to those with non-carbazole-containing fluorene spacer (P2 and M2). Upon photoexcitation, each of P1 and M1 emits an intense purple-blue fluorescence emission in the near-UV to visible region in dilute fluid solutions at room temperature. Harvesting of organic triplet emissions harnessed through the strong heavy-atom effects of platinum metal was examined and at 77 K, each of the metalated compounds displayed dual emission bands, viz. both the fluorescence and the lower-lying phosphorescence. Spectroscopic results revealed that the formation of excimers was suppressed by introducing carbazole side groups. The spatial extent of the lowest singlet and triplet excitons in P1 and M1 was fully elucidated. Such organometallic poly(fluorenyleneethynylene)s anchored with the carbazole pendants was found to have an improved thermal stability and suppressed aggregation.