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We demonstrated that a synthetic ligand NA, which selectively binds to a 5′-CAG-3′/5′-CAG-3′ triad, induced repeat contractions during DNA polymerase-mediated primer extension through the CAG repeat template. A thorough capillary electrophoresis and sequencing analysis revealed that the d(CAG)20 template gave shortened nascent strands mainly containing 3–6 CTG units in the presence of NA.

Fluorescent labels and probes constitute an important class of organic materials used in the development of sensor systems and imaging platforms for various chemical and molecular biology applications. In the development of fluorescent labels and probes, multichromic environment-sensitive fluorophores are very important. In this work, novel triad systems, including subphthalocyanine, BODIPY and thiophene/thianaphthene units, were prepared and their molecular structures were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 1H and 13C NMR spectroscopy. The optical properties of the subphthalocyanine–BODIPY–thiophene/thianaphthene triads were determined using UV-vis absorption and fluorescence (2D and 3D) spectroscopic methods and quantum chemical calculations. The data were analyzed by comparing the results of the final properties to those of the BODIPY- and subphthalocyanine-alone units. The compounds were also evaluated in live cell imaging using a breast cancer cell line. The novel subphthalocyanine–BODIPY–thiophene/thianaphthene triads displayed dual color emission, which is critically important for the development of novel systems particularly in biomedical applications such as bioimaging and cellular sensor systems.

Two supramolecular cobalt(II) porphyrin–fullerene systems, (PyC60)2CoDTBCP/(Py2C70)CoDTBCP, self-assembled via axial coordination of 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero[60]pyrrolidine and 2,5-di-(pyridin-2-yl)-3,4-fullero[70]pyrrolidine by (5,15-bis[3,5-bis(tert-butyl)phenyl]-10,20-bis[4,6-(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)pyrimidin-5-yl]porphinato)cobalt(II), respectively, were prepared and characterized for the first time. Target carbazole-functionalized cobalt(II) porphyrin was synthesized by direct metallation of the corresponding porphyrin that was in its turn obtained by tetra-substitution of 5,15-bis[4,6-dichloropyrimidin-5-yl]porphyrin with 4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenol. All compounds synthesized were fully characterized by mass spectrometry and UV-vis, IR, and 1H NMR spectroscopy. Chemical structure and spectral properties of the triad/dyad were additionally described using chemical thermodynamics, kinetics, and DFT calculations. The analysis of the geometric and electronic structures of the (PyC60)2CoDTBCP and (Py2C70)CoDTBCP FMOs in the ground state and the study of their femtosecond transient absorption spectra points to the existence of photoinduced electron transfer in the triad and dyad. The data obtained are required for further photoelectrochemical study of the triad/dyad and determining their potential in the building of photovoltaic devices.

Oxidation of M(CO)6 (M = Cr, Mo, W) with the synergistic oxidative system Ag[WCA]/0.5 I2 yields the fully characterized metalloradical salts [M(CO)6]+˙[WCA]− (weakly coordinating anion WCA = [F-{Al(ORF)3}2]−, RF = C(CF3)3). The new metalloradical cations with M = Mo and W showcase a similar structural fluxionality as the previously reported [Cr(CO)6]+˙. Their reactivity increases from M = Cr < Mo < W and their syntheses allow for in-depth insights into the properties of the group 6 carbonyl triad. Furthermore, the reaction of NO+[WCA]− with neutral carbonyl complexes M(CO)6 gives access to the heteroleptic carbonyl/nitrosyl cations [M(CO)5(NO)]+ as salts of the WCA [Al(ORF)4]−, the first complete transition metal triad of their kind., The triad of group VI metalloradicals is now finally accessible via the oxidation of Cr/Mo/W(CO)6 with the synergistic oxidative system Ag[F-{Al(ORF)3}2]/0.5 I2.

Structure-property relationships of donor-π-acceptor (D-π-A) type molecular dyad (pp-AD) and triads (pp-ADA and Me-pp-ADA) based on benzodithiophene and BODIPY with biphenyl spacers have been reported. Rotors pp-AD and pp-ADA showed efficient twisted intramolecular charge transfer (TICT) with near infrared (NIR) emissions at ∼712 nm and ∼725 nm with (pseudo-)Stokes shifts of ∼208 nm and ∼221 nm, respectively, and prominent solvatochromism. A structurally similar triad, Me-pp-ADA, with tetramethyl substituents on the BODIPY core instead was TICT inactive and exhibited excitation energy transfer with a transfer efficiency of ∼88% as revealed using steady state emission and transient absorption measurements. Rotors pp-AD and pp-ADA showed NIR emission with an enhancement in intensity with the addition of water in THF solution as well as a pronounced change in emission intensity with temperature and viscosity variations, which justify their utility as temperature and viscosity sensors. Furthermore, the linear correlation of lifetime with fluorescence intensity ratios of the donor and acceptor justifies the rigidochromic behaviour of these rotors.

A multichromophoric triad, ZnP–OxP–C60 containing porphyrin (ZnTPP hereafter ZnP), oxoporphyrinogen (OxP) and fullerene (C60) has been synthesized to probe the intramolecular dynamics of its electron and energy transfer in relation to the presence of the closely linked electron deficient OxP–C60 ‘special pair’, constructed as a mimic of the naturally occurring photosynthetic antenna-reaction center. The DFT optimized structure of the triad reveals the relative spatial remoteness of the ZnP entity with proximal OxP/C60 entities. Free-energetics of different energy and electron transfer events were estimated using spectral, computational and electrochemical studies, according to the Rehm–Weller approach. Femtosecond transient absorption spectral studies revealed energy transfer from 1ZnP* to OxP to yield ZnP–1OxP*–C60, and electron transfer to yield ZnP˙+–OxP–C60˙− and/or ZnP–OxP˙+–C60˙− charge seperated states. That is, the ZnP entity in the triad operates as both antenna and electron donor to generate relatively long-lived charge separated states thus mimicking the early photoevents of natural photosynthesis.

A new family of ten dinuclear Ru(II) complexes based on the bis[pyrrolyl Ru(II)] triad scaffold, where two Ru(bpy)2 centers are separated by a variety of organic linkers, was prepared to evaluate the influence of the organic chromophore on the spectroscopic and in vitro photodynamic therapy (PDT) properties of the compounds. The bis[pyrrolyl Ru(II)] triads absorbed strongly throughout the visible region, with several members having molar extinction coefficients (e) ≥ 104 at 600–620 nm and longer. Phosphorescence quantum yields (Φp) were generally less than 0.1% and in some cases undetectable. The singlet oxygen quantum yields (ΦΔ) ranged from 5% to 77% and generally correlated with their photocytotoxicities toward human leukemia (HL-60) cells regardless of the wavelength of light used. Dark cytotoxicities varied ten-fold, with EC50 values in the range of 10–100 μM and phototherapeutic indices (PIs) as large as 5400 and 260 with broadband visible (28 J cm−2, 7.8 mW cm−2) and 625 nm red (100 J cm−2, 42 mW cm−2) light, respectively. The bis[pyrrolyl Ru(II)] triad with a pyrenyl linker (5h) was especially potent, with an EC50 value of 1 nM and PI > 27 000 with visible light and subnanomolar activity with 625 nm light (100 J cm−2, 28 mW cm−2). The lead compound 5h was also tested in a tumor spheroid assay using the HL60 cell line and exhibited greater photocytotoxicity in this more resistant model (EC50 = 60 nM and PI > 1200 with 625 nm light) despite a lower dark cytotoxicity. The in vitro PDT effects of 5h extended to bacteria, where submicromolar EC50 values and PIs >300 against S. mutans and S. aureus were obtained with visible light. This activity was attenuated with 625 nm red light, but PIs were still near 50. The ligand-localized 3ππ* state contributed by the pyrenyl linker of 5h likely plays a key role in its phototoxic effects toward cancer cells and bacteria.

Metalloenzymes catalyze many important reactions by managing the proton and electron flux at the enzyme active site. The motifs utilized to facilitate these transformations include hemilabile, redox-active, and so called proton responsive sites. Given the importance of incorporating and understanding these motifs in the area of coordination chemistry and catalysis, we highlight recent milestones in the field. Work incorporating the triad of hemilability, redox-activity, and proton responsivity into single ligand scaffolds will be described.

A fluorescent D–A–D′ triad (1), composed of monocarbaborane, benzothiadiazole and triphenylamine, was synthesized. By replacing monocarbaborane with phenyl (Ph), p-methoxyphenyl (PMP) or 4-pyridinyl (Py), three analogs (2, 3, and 4) were prepared for comparison. Monocarbaborane is an electron donating group based on the comparative analysis of NMR spectra and the systematic investigation of their photophysical properties. Triad 1 emits bright-yellow light in THF solution with the highest quantum yield and the longest decay time among these compounds. It tends to form nanoparticles in aqueous THF solution. The in situ generated nanoparticles might be used to detect silver ions with high sensitivity and high selectivity. By holding the molecules via multiple CH⋯π interactions and electrostatic forces between the tetraethylammonium cation and the cage, a sheet-like arrangement of 1 is formed in the solid state with the smallest crystal density that provides the maximal possibility of mechanofluorochromism from the crystalline to the ground form. Moreover, by doping 1 in PVK, a white OLED is obtained.

Three series of monohalophenyl-N-pyridinylcarbamate isomer grids (CxxX) are reported (with x = para-, meta-, ortho; X = fluorine, chlorine, bromine), and Cx as the aminopyridinyl group (C5NH4NH–) and xX as –CO2C6H4X. Nine crystal structures are presented with all nine structures aggregating via N–H⋯N intermolecular interactions as their primary hydrogen bond; as chains in CmpX, CmmX and as dimers in the CopX triad. Halogen bonding is absent and there is a preference for N–H⋯N and C–H/π⋯π stacking intermolecular interactions. Structural similarities abound with all three CmpX structures isomorphous in space group Pc and with CopF and CopCl isomorphous in P (No. 2). Differences between the monohalogenated CxxX carbamates and their CxxM and CxxOMe relatives (M, OMe = methyl, methoxy) are discussed, especially the reluctance of CxxX to form quality single crystals as most crystallise as filamentous-like fibres under a range of crystallisation conditions. Conformational analyses of the three [3 × 3] CxxX isomer grids of minimized structures in gas-phase are detailed for comparisons with the solid-state structures. Modelling results reveal inherent steric problems in CxoX associated with bulky pendant ortho-groups (i.e. bromine). Physicochemical analyses including melting point analysis and solid-state correlations are rationalised. A question is posed as to why the CxxX carbamates are reluctant to crystallise as quality single crystals and with a higher incidence of Z′ > 1 in comparison with related carboxamides.

A homotrimetallic manganese(iii) corrole-porphyrin-corrole triad has been synthesized and structurally characterized. Corrole and porphyrin rings in the free base corrole-porphyrin-corrole triad are found to be roughly perpendicular to each other having a dihedral angle of 83° in the solid state. A dihedral angle of nearly 67° was found between Mn(iii)-corroles and Mn(iii)-porphyrin rings in the manganese triad complex, 1-Mn. The absorption spectrum of the manganese triad was observed to be the sum of the absorptions from manganese corrole and manganese porphyrin. The catalytic activity of the manganese triad complex was investigated for the epoxidation of styrene using iodobenzene diacetate as an oxygen source. Preliminary results obtained showed the superior activity of the manganese triad as an oxidation catalyst as compared to the respective monomer catalysts. Moreover, product yield in the oxidation of styrene catalyzed by the manganese triad was found to be higher than that of the combined activity of both monomers taken in same equivalence. The reason behind this higher yield may be attributed to an increased local concentration of the catalytic centers at the reaction site.

Two new compounds, BODIPY–tetraphenylethylene dyad and BODIPY–o-carborane–tetraphenylethylene triad, were designed and synthesized. This molecular dyad and triad have been characterized by using various spectroscopic methods, including FT-IR, mass, UV-visible absorption and fluorescence emission spectroscopy, and one and two-dimensional homo- and hetero-correlated NMR spectroscopy. Photophysical properties, as well as solvatochromic and aggregation-induced emission (AIE) behavior, have been investigated. Single-crystal X-ray diffraction analysis has unambiguously revealed their structure and provides an explanation for the absence of AIE character. The redox properties showed that an o-carborane addition increased the reduction potential and shifted the oxidation potential to the positive site.

Photoinduced electron transfer via hopping is generally considered to have a stronger temperature dependence than electron transfer via superexchange. However, in this work, an opposite trend of the temperature dependence is observed. This unexpected result is rationalized by considering the specific geometrical and electronic structure of the Ru-bis(terpyridine) photosensitizer.

Functionalized meso-tetraaryl triphyrins(2.1.1) containing two meso-iodophenyl groups or a bromo group at the β-pyrrole carbon were synthesized over a sequence of steps. The covalently linked conjugates such as a triphyrin(2.1.1)-(ferrocene)2 triad and a triphyrin(2.1.1)-ferrocene dyad were obtained in 47-51% yields by coupling the appropriate functionalized triphyrin with ethynylferrocene under mild Pd(0) coupling reaction conditions. The functionalized triphyrins(2.1.1) and their conjugates were thoroughly characterized by HR-mass spectrometry and 1D and 2D NMR spectroscopy. The absorption, electrochemical and DFT studies suggested weak interactions between the triphyrin(2.1.1) and ferrocenyl moieties in triads but relatively strong interactions in dyads.

High triad isotacticity (mm = 69%) in copper/BOX mediated ATRP of MMA is achieved. The use of strong Lewis acid Yb(NTf2)3 (1.0–8.0 mol%) and HFIP as the solvent is the key for this isotactic stereocontrol. A dilute concentration and a relatively low temperature are beneficial for further improving the isotacticity.

Excitation transfer from 1BODIPY* to bisstyrylBODIPY followed by electron transfer to C60 leading to a charge separated state of appreciable lifetime in a supramolecularly assembled triad is demonstrated, as a mimic of the photosynthetic ‘antenna-reaction centre’.

Three, broad band capturing, vertically aligned supramolecular triads, R2-BDP-AlPorF3←Im-C60 [R = H, styryl (C2H2-Ph), C2H2-TPA (TPA = triphenylamine); ← = coordinate bond], have been constructed using BODIPY derivative (BDP, BDP-Ph2 or BDP-TPA2), 5,10,15,20-tetrakis(3,4,5-trifluorophenyl)aluminum(iii) porphyrin (AlPorF3) and fullerene (C60) entities. The C60 and BDP units are bound to the Al center on the opposite faces of the porphyrin: the BDP derivative through a covalent axial bond using a benzoate spacer and the C60 through a coordination bond via an appended imidazole. Owing to the bis-styryl functionality on BDP, the constructed dyads and triads exhibited panchromatic light capture. Due to the diverse absorption and redox properties of the selected entities, it was possible to demonstrate excitation wavelength dependent photochemical events. In the case of the BDP-AlPorF3 dyad, selective excitation of BDP resulted in singlet-singlet energy transfer to AlPorF3 (kEnT = 1.0 × 1010 s-1). On the other hand, excitation of the AlPorF3 entity in the BDP-AlPorF3←Im-C60 triad revealed charge separation leading to the BDP-(AlPorF3)˙+-(C60)˙- charge separated state (kCS = 2.43 × 109 s-1). In the case of the Ph2-BDP-AlPorF3 dyad, energy transfer from 1AlPorF3* to 1(Ph2-BDP)* was witnessed (kEnT = 1.0 × 1010 s-1); however, upon assembling the supramolecular triad, (Ph2-BDP)-AlPorF3←Im-C60, electron transfer from 1AlPorF3* to C60 (kCS = 3.35 × 109 s-1), followed by hole shift (kHS = 1.00 × 109 s-1) to Ph2-BDP, was witnessed. Finally, in the case of the TPA2-BDP-AlPorF3←Im-C60 triad, only electron transfer leading to the (TPA2-BDP)˙+-AlPorF3←Im-(C60)˙- charge separated state, and no energy transfer, was observed. The facile oxidation of Ph2-BDP and TPA2-BDP compared to AlPorF3 in the latter two triads facilitated charge separation through either an electron migration or hole transfer mechanism depending on the initial excitation. The charge-separated states in these triads persisted for about 20 ns.

An acceptor–donor–acceptor (A–D–A) triad based on a BODIPY acceptor and a benzodithiophene donor exhibited dual fluorescence and pronounced fluorescence solvatochromism because of twisted intramolecular charge transfer (TICT) state formation. Furthermore, it showed a Stokes shift of ∼194 nm which is the highest known for any BODIPY compound with a readily tunable fluorescence and a high charge carrier mobility of 4.46 × 10−4 cm2 V−1 s−1.

A novel porphyrin–BODIPY dyad, where BODIPY acts as the central antenna, linked via the Sonogashira coupling reaction, and a novel porphyrin–o-carborane–BODIPY triad, where both porphyrin and BODIPY are covalently attached to the o-carborane, have been synthesised and characterised. X-ray crystallography confirmed a V-shaped triad molecule. Detailed studies on the photophysical properties revealed the excitation of the BODIPY dyad system, which selectively triggered an efficient resonance energy transfer to the porphyrin unit. The presence of the o-carborane group in the triad system significantly diminished the energy transfer efficiency from BODIPY to the porphyrin moiety, because of its quenching properties. Besides, the triad system displayed aggregation-enhanced emission in THF/water systems, due to the presence of the o-carborane unit. The in-depth investigation of the electrochemical properties demonstrated that o-carborane insertion extended the initial reduction potentials and shifted half waves from the anodic to the cathodic site.

Self-assembly by donor–acceptor complex formation in the (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(2-pyridyl)porphinato)cobalt(II) (CoIIP)–1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4′:1,2][60]fullerene (PyC60) system was studied using chemical thermodynamics/kinetics, UV-vis, IR, 1H NMR spectroscopy, amperometry and quantum chemical B3LYP-D3/6-31G(d,p) methods. The results revealed the formation of a supramolecular 1 : 2 triad between CoIIP and PyC60. The equilibrium/rate constants of the donor–acceptor triad formation are observed to be (1.04 ± 0.12) × 1010 L2 mol−2 and (63.7 ± 4.5) mol−1 L s−1, respectively. The numerical values of these equilibrium/rate constants demonstrate a strong bonding between the CoIIP and fulleropyrrolidine moieties. The triad LUMO energy levels are predominantly spread on the C60 unit. However, the HOMO energy levels are mainly spread on the porphyrin ring pointing at the property of photoinduced electron transfer (PET) in the obtained triad. Modification of the covered natural oxide film titanium electrode surface in the voltammetry experiment was carried out by using the porphyrin–fullerene triad and the self-assembly components. The maximum efficiency coefficient of the incident photon energy conversion to current (IPCE) and photocurrent density values of (PyC60)2CoIIP at 365 nm are significantly larger than those of CoIIP and PyC60. The results are of interest for creating porphyrin-based donor–acceptor systems as components in organic photovoltaics.

The modular assembly of a directional photoredox-active multidonor-photosensitizer-multiacceptor (Dn-P-Am) architecture is presented. The triad assembly features a central Ru(ii) sensitizer equipped with pendant polymer chains consisting of multiple triarylamine (pTARA) and naphthalene diimide (pNDI) units, respectively. Upon excitation, the efficient formation (>96%) of charge separation (CS) was observed featuring similar CS lifetimes (400 ns) as related molecular triads. In contrast, a significant additional longer-lived CS component (2400 ns, 30%) is observed indicating multiple contributing pathways.

As a member of the histidine triad (HIT) protein superfamily, human histidine triad nucleotide binding protein 1 (hHint1) serves as an efficient enzyme in the hydrolysis of phosphoramidate. In particular, hHint1 has been utilized to activate nucleotide prodrugs (proTides). Understanding the mechanism of hHint1 will aid in the future design of proTides. Density functional theory (DFT) computations on a 228-atom cluster active-site model were performed to investigate the hydrolysis mechanism of a phosphoramidate substrate. The overall proposed mechanism included the key involvement of the histidine triad as a proton shuttle. Protonated methylphosphoramidate was first formed by proton transfer of protonated His114 species. A penta-coordinated phosphoryl intermediate, protonated methylphosphorodiamidate, was generated by a nucleophilic attack of His112. After the release of amine and the generation of a phosphorylated histidine intermediate, the nucleophilic attack of an active-site water produced a hydrolyzed intermediate that subsequently transferred a proton back to His114. A rate-determining fully associative pathway with a free energy of activation of 21.7 kcal mol-1 formed the penta-coordinated phosphoryl intermediate. A non-rate determining associative-interchange transition state was involved in the formation of transient tetra-coordinated phosphoryl intermediate. The overall hydrolysis was favorable by -16.1 kcal mol-1.

Sandwich complexes are important building blocks in medicinal inorganic chemistry for group 6 and 8 elements but are almost unknown for the manganese triad. We present the syntheses and full characterization of the mixed-arene 99Tc sandwich complexes [99Tc(η6-hmbz)(η6-C6H5–NH3)](PF6)2 and [99Tc(η6-hmbz)(η6-C6H5–Br)](PF6). Both comprise functionalities for conjugation to targeting molecules or for being included as substructures in pharmaceutically active lead compounds. Since η6-benzene ligands are too stably bound to be replaced with incoming ligands, we prepared naphthalene complexes [Re(η6-C6H6)(η6-napht)]+ and [Re(η6-napht)2]+. Their reactivities towards substitution are increased and one or both naphthalene ligands can be replaced with mono- or multi-dentate ligands. Combining the features of 99Tc and Re may lead to a molecule-based theranostic approach.

In this paper, we report a theoretical investigation of the catalytic mechanism of peptide amidases that involve a Ser-(cis)Ser-Lys catalytic triad. Previous suggestions propose that these enzymes should follow a distinct catalytic mechanism from the one that is present in the classic Ser-His-Asp catalytic triad. The theoretical and computational results obtained in this work indicate the opposite idea, showing that both mechanisms are very similar and only few differences are observed between both reactions. The results reveal that the different alignment of the Ser-(cis)Ser-Lys catalytic triad in relation to the classical Ser-His-Asp triad may provide a better stabilisation of the reaction intermediates, and therefore make these enzymes catalytically more efficient. The catalytic mechanism has been determined at the M06-2X/6-311++G**//B3LYP/6-31G* level of theory and requires five sequential steps instead of the two that are generally proposed: (i) nucleophilic attack of serine on the carbonyl group of the substrate, forming the first tetrahedral intermediate, (ii) formation of an acyl-enzyme complex, (ii) release of an ammonia product, (iv) nucleophilic attack of a water molecule forming the second tetrahedral intermediate, and (iv) the release of the product of the reaction, the carboxylic acid. The computational results suggest that the rate-limiting step is the first one that requires an activation free energy of 15.93 kcal mol-1. This result agrees very well with the available experimental data that predict a reaction rate of 2200 s-1, which corresponds to a free energy barrier of 14 kcal mol-1.

We have prepared a crown ether triad containing acylhydrazone units. In solution, the triad can self-assemble linearly to form an organogel. UV light-induced E/Z isomerization of the CN bond of the acylhydrazone unit endows the assembly with photo-sensitivity. The triad was able to insert into the lipid bilayer to form a supramolecular transmembrane channel which showed transport selectivity for NH4+ over K+. The channel exhibited photo-gating properties under microscopic and macroscopic conditions. The transport of the channel could be reversibly switched off and on by irradiation with alternating 320 and 365 nm UV light as supported by the conductance measurements.

Lauric diacid (LCDA), also known as 1,12-dodecanedioic acid, is used to develop a series of copolyesters along with 1,4-cyclohexanedicarboxylic acid (CHDA) and 1,4-butanediol (BDO). The resulting poly(butylene lauric dicarboxylate-co-butylene 1,4-cyclohexanedicarboxylate) (PBLC) is proved to be a random copolyester with three triad sequences. When the LCDA content increases from 20 to 60 mol%, Tm of the copolyester decreases from 133 to 57 °C. At the same time, the tensile modulus and strength decrease from 94 and 14 MPa to 40 and 5 MPa, respectively. Moreover, the elongation at break also drops from 640 to only 50%. However, further increasing the LCDA content to 80 mol%, the copolyester becomes amorphous with no Tm, and its tensile modulus, strength, and the elongation at break all improve significantly to 68 and 7 MPa, and over 1400%, respectively. More importantly, for the homo-polymer poly(butylene lauric dicarboxylate) (PBL), it has a relatively high Tm of 73 °C compared to that of polycaprolactone (PCL), but lower tensile modulus and strength, and significantly higher ductility, compared to those of PCL, linear low density polyethylene, and polybutylene succinate.

The first near-infrared fluorescent and columnar liquid crystal based on Bodipy was achieved by modifying 3,5-alkenyl substituted Bodipy with two triphenylene units. Triphenylene-Bodipy-triphenylene triad with 3,5-alkenyl groups exhibited hexagonal columnar mesophase and near-infrared fluorescence at 650–800 nm with the quantum yield of 31%.

The synthesis and characterization of a subphthalocyanine–azobenzene–subphthalocyanine triad is reported. Evidence for trans ↔ cis isomerization of the linking azobenzene moiety is observed in the NMR and optical spectra when the subphthalocyanine rings are used as light-harvesting units. Significantly, a decrease in fluorescence intensity is observed on moving from trans → cis with a recovery in intensity observed on moving back from cis → trans that can be attributed to a change in the rate of non-radiative decay.

Poly(3-hexylthiophene) (P3HT) is one of the most widely studied conjugated polymers for applications in polymer-based photovoltaics and thin-film transistors. The regioregularity index (RR) represented by the mole percentage of the head-to-tail (HT) dyad in the polymer molecule has been considered as a key factor governing both the kinetics and thermodynamics of the self-assembly of P3HT. In this study, we reveal that the configurational sequence beyond dyad plays an equally important role by demonstrating that two P3HT samples bearing almost identical RR value and average molecular weight displayed very different self-assembly kinetics. Counterintuitively, the semidilute xylene solution of the P3HT with slightly smaller RR value exhibited a much faster gelation. In the bulk state, this sample also showed faster crystallization kinetics and higher melting point. Characterization of the configurational structure by nuclear magnetic resonance (NMR) spectroscopy showed that the P3HT with the smaller RR value contained a higher population of HT-HT triad sequence. Therefore, knowledge of this system parameter, which has been omitted prevalently, is essential for the delicate control of the morphological formation of P3HT for enhancing its photophysical properties.

The development of an efficient and affordable bifunctional electrode for full water splitting in basic and neutral conditions is still a challenging issue in obtaining clean and sustainable chemical fuels. Herein, a unique bifunctional electrode consisting of 3D trinary transition-metal phosphide nanosheets with abundant reactive sites anchored on Ni foam, referred to as FexCoyNizP, has been developed through a facile two-step process of electrodeposition and low-temperature phosphidation. When used as a bifunctional electrode for the full water splitting, an applied voltage of 1.57 V is required for a current density of 10 mA cm−2.

The synthesis and characterization of a subphthalocyanine–bisazobenzene–subphthalocyanine triad are reported. Evidence for E,E ↔ E,Z isomerization of the linking bisazobenzene moiety is observed in the optical and NMR spectra when the subphthalocyanine rings are used as light-harvesting units. Electronic coupling and communication between the two para-azo units decrease the photoisomerization efficiency. An obvious decrease in fluorescence intensity is observed on moving from E → Z with a recovery in intensity observed on moving back from Z → E that can be attributed to a change in the rate of non-radiative decay.

An efficient copper-catalyzed direct arylation reaction for the regioselective functionalization of benzodithiophene-S,S-tetraoxide has been developed. The method demonstrates a broad scope with isolated yields ranging from good to excellent. Furthermore, the reaction specificity for aryl iodides over the unreactive aryl bromides provide a opportunity to generate a new donor-acceptor-donor triad.

The synthesis and structure of a multichromophore triad consisting of two anthracene units axially bound to a Sn(IV)porphyrin centre via the carboxylate functionality has been reported, in which two anthracene moieties of two neighboring molecules generate a 1D polymeric chain. The fluorescence intensity of the axially coordinated 9-anthracenecarboxylic acid (9-ACA) in triad (excited at 330 nm) is significantly quenched due to the efficient singlet-to-singlet energy transfer from the excited state of 9-ACA to Sn(IV)porphyrin. The effective energy transfer from axial anthracene to equatorial porphyrin makes the triad a rare example amongst anthracene–porphyrin donor–acceptor systems. The triad shows excimer-type structureless emission band at around the 470 nm region in the concentration >10−5 M because of the strong π–π interaction between the two anthracene moieties of neighboring molecules, which is also evident from the solid-state structure of the complex.

We synthesized three dumbbell-like compounds 2a-c, each containing two C-60 groups at the periphery and pyromellitic diimide (PMDI) in the middle, and examined their electronic as well as assembly characteristics with both experimental and computational methods. Cyclic voltammetry (CV) measurements revealed that each of three electron-accepting (AAA) triads could accommodate up to eight electrons. Computational studies (density functional theory, DFT) of 2a-c at PBEPBE/6-311G(d, p) level of theory, with B3LYP/6-31G(d) optimized geometries, revealed that HOMO-LUMO energy gaps are similar to those of the model compound [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM). Compounds 2a-c were also found to assemble into vesicles and nanoparticles on the copper grid (100-300 nm, TEM), while giving more sizeable aggregates after a deposition on the glass (SEM, gt 5 mm). Understanding the packing of 2a-c on various solid substrates, as well as the assembly characteristics in general, is important for tuning the properties and fabrication of electronic/optical devices. On the basis of the results of conformational analysis (MM and DFT calculations), we deduced that different alkyl spacers in 2a-c ought to play a role in pi-pi interactions between the aromatic components of the triad to guide the packing and therefore morphology of the material. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3369]

A photoswitchable fluorescent triad based on dithienylethene and Bodipy was used as a triplet acceptor/emitter for reversible photoswitching of triplet-triplet-annihilation upconversion (with Pd(II) tetraphenyltetrabenzoporphyrin as a triplet photosensitizer), which shows green/near IR emission changes with an emission energy difference of 0.79 eV (Δλ = 268 nm).

An electron-rich phthalocyanine–thiophene–phthalocyanine triad 3 (Pc-triad 3), newly synthesized, can function as a highly selective chemosensor against picric acid (PA). Pc-triad 3 showed efficient and selective fluorescence quenching towards PA, during which a photo-induced electron transfer (PET) complex arose from the electron-rich pendant Pc rings of 3 to the PA reagents.

The Ni triad [M(R2pipdt)(dmit)] based on donor/acceptor S,S′ ligands, where R2pipdt = 1,4-diisopropyl-piperazine-2,3-dithione (acceptor) and dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato (donor), was completed by preparing and characterizing the Pd(2) and Pt(3) compounds in addition to the already known Ni(1) complex. The rationale behind the work was to compare the properties and structures inside the triad with those of the corresponding Ni(4), Pd(5) and Pt(6) complexes where R = Bz. Minor changes in the properties as redox active nonlinear second-order (NLO) chromophores were observed in solution for the two triads. Instead, different structural features, reflected by changes in the diffuse reflectance spectra, were observed in their crystals on changing R from Bz to Pri in the piperazine ring and also, more surprisingly, inside the triads. 2 (isostructural with 1) and 3 crystallized in monoclinic P21/n and orthorhombic Pbca space groups, respectively. The crystal packings of 2 and 3 are also markedly different. In particular 1 and 2 form head-to-tail dimers whereas 3 forms supramolecular layers characterized by a partial stack between the molecular planes. Large differences in the crystal structures, induced by the diverse number and types of interactions exchanged by the peripheral fragments of the ligands, were found in the Bz-triad. Indeed, the molecules are stacked in a head-to-head and in a head-to-tail fashion in 4 and in 5/6, respectively. Moreover, significantly different packings were observed. The Hirshfeld surface analysis was used to provide a detailed description of the main types of interactions involved in the crystal packing of the six complexes.

Anchoring a BODIPY onto Ga(III)corrole via a meso-β linkage facilitated PeT in polar solvents, which quenched the fluorescence, and is further confirmed by electrochemical studies. The triad exhibits unprecedented crystal emission, which is not known for a corrole derivative, due to unique packing. Compound 4 hosts the first example of a novel B-F∙∙∙F interaction as well.

A V-configured subphthalocyanine-azaBODIPY-C60 supramolecular triad has been newly synthesized, and sequential energy and electron transfer leading to the formation of charge separated states, useful properties relevant for solar energy harvesting and building optoelectronic devices, is reported.

Amine-containing stereotriads (‘triads’), where the nitrogen is embedded in an array of three contiguous, heteroatom-bearing chiral carbons, are key motifs in numerous bioactive natural products. Allene aziridination provides convenient access to amine triads where the position of the nitrogen and the identities of the accompanying heteroatoms can be readily manipulated. However, stereochemical flexibility, where a single allene can be selectively transformed into any possible diastereomer of a specific triad, has been elusive. Herein, we describe studies to understand how both reagent and substrate control can be effectively employed in the stereodivergent oxidative amination of allenes, with transfer of the axial chirality of an enantioenriched precursor to point chirality in each possible diastereomeric 2-amino-1,3-diol product. Application of this flexible strategy to the synthesis of all four stereoisomers of the natural product detoxinine is also presented.

A series of novel multi-component chromophores, one phthalocyanine–perylenediimide–phthalocyanine triad and two phthalocyanine–perylenediimide dyads, were synthesized by covalent linkage between phthalocyanines and perylene-3,4,9,10-bis(dicarboximide) at the bay position of perylene core in one condensation reaction. The photophysical properties of the dyes were presented with wider light absorption from 300 to 800 nm and discussed by interpretation and correlations with previous dyes. Density functional theory at the B3LYP level with 6-31G(d) was performed for geometry and energy optimization. Furthermore, a substitution and elimination reaction at the perylene bay position by using 1,8-diazabicyclo[5,4,0]undec-7-ene as catalyst was performed and its probable mechanism discussed.

A tri-metallic triad based on a [Ru(bpy)3](2+) moiety connected to Fe(ii) and Co(iii) bisterpyridine has been grafted on an ITO electrode by a stepwise procedure. Under visible light, in the presence of a sacrificial electron donor, the system produces electric current. The photo-current magnitude is compared to the one generated from a Co(iii)-Ru(ii) dyad and shows an increase of 40%.

A novel nanorod-like inorganic-organic hybrid compound based on polyoxometalate architectures and organic linkers was successfully synthesized, which exhibits reversible reduction-oxidation properties and fascinating photochromism under sunlight illumination.

Proteinosomes comprising a triad of enzyme–polymer amphiphilic building blocks capable of operating together as a multi-step membrane-mediated cascade system are prepared and characterized.

A new dyad and two triad chromophore compounds containing coumarin, Ru(II) and Os(II) terpyridine-type complexes were synthesized. The dyad is composed of coumarin and Os(II) units, while the triads are composed of coumarin, Ru(II) and Os(II) units. One of the triads has a phenylene spacer to connect the Ru(II) unit and the Os(II) unit, while the other has an azo moiety. Energy transfer in these multichromophoric systems has been probed by electronic absorption and luminescence spectroscopy. The switching behavior of photo-induced energy transfer by redox stimuli in the latter triad has been examined. Photophysical and electrochemical analysis indicates that the contribution of the energy transfer from the coumarin chromophores and the Ru(II) center to the Os(II)-centered emission in the ‘switch-on state’ is estimated to be about 70%. This contribution is larger than that in the previously reported Ru(II)/Os(II) dyad system, which was evaluated to be 40%. Thus, it is concluded that an improved switching of directional energy transfer has been achieved from the coumarin moiety to the Os(II) center in this new triad chromophore system.

An improved preparation of the bulky tris(mercaptoimidazolyl)borate ligand [TmtBu]− is reported together with convenient high yield syntheses of the Group 12 metal derivatives [TmtBu]MBr (M = Zn, Cd, Hg). The molecular structures of the three new complexes have been determined by single-crystal X-ray diffraction and together constitute the first complete triad of TmR compounds in the periodic table to be structurally characterized. The isostructural complexes display in the solid state distorted tetrahedral structures, with the heavier members of the group exhibiting larger Br–M–S and smaller S–M–S angles.

We present the design of molecular materials for ultimate use in solid-state solar cells. The molecular materials are semi-rigid oligomeric rods of defined length with metalloporphyrins in the backbone and a carboxy group at one end for attachment to a surface. The rods are designed to absorb visible light, and then undergo excited-state energy transfer and ground-state hole transfer in opposite directions along the length of the rod. The rational synthesis of the multiporphyrin arrays relies on joining porphyrin building blocks in an efficient and controlled manner. Several porphyrin building blocks have been synthesized that bear bromophenyl, iodophenyl, trimethylsilylethynylphenyl and/or ethynylphenyl substituents for use in a copper-free Sonogashira reaction using Pd2(dba)3 and P(o-tol)3. Competition experiments performed on equimolar quantities of an iodo-porphyrin and a bromo-porphyrin with an ethynyl-porphyrin show iodo + ethyne coupling with a low amount (35 °C) or undetectable amount (22 °C) of bromo + ethyne coupling. Efficient coupling of bromo-porphyrins with ethynyl-porphyrins was achieved using the same copper-free Sonogashira reaction conditions at higher temperature (50 °C or 80 °C). These findings allow successive coupling reactions to be achieved using substrates bearing iodo and bromo synthetic handles. Thus, a porphyrin-based tetrad (or pentad) was synthesized with a final convergent coupling of a bromo-substituted dyad (or triad) and an ethynyl-substituted dyad. A porphyrin triad was prepared by sequential iodo + ethyne coupling reactions. The triad, tetrad, and pentad each are comprised of a terminal magnesium porphyrin bearing one carboxy group (for surface attachment) and two pentafluorophenyl groups; the remaining porphyrins in each array are present as the zinc chelate. Electrochemical characterization of benchmark porphyrins indicates the presence of the desired electrochemical gradient for hole hopping in the arrays. Static absorption data indicate that the arrays are weakly coupled, while static fluorescence data indicate that the excited-state energy flows in high yield to the terminal magnesium porphyrin. Time-resolved spectroscopic analysis leads to rate constants in THF of (9 ps)−1, (15 ps)−1, and (30 ps)−1 for ZnMg dyad 20, Zn2Mg triad 13, and Zn3Mg tetrad 15, respectively, and quantum efficiencies ≥99% for energy flow to the magnesium porphyrin in each case. These design and synthesis strategies should be useful for the construction of materials for molecular-based solar cells.

The preparation, spectroscopic, and structural characterization of four gold(I) complexes, (o-xylylNC)AuX with X as I, Br, Cl or CN, are reported. Each crystallizes in a unique, solvent-free form with varying aurophilic interactions between the linear, two-coordinate molecules. Thus, (o-xylylNC)AuCl forms a simple dimer, while the bromo and iodo analogs form slightly kinked chains with extended Au· · ·Au· · ·Au· · · units. The bromo complex differs from the iodo complex due to the fact that an independent, non-interacting (o-xylylNC)AuBr unit lies off to the side of the linear chain. The structure of (o-xylylNC)AuCN consists of a complex grid which involves kinked chains of gold atoms cross linked by another aurophilically connected triad of gold centers. The complexes are all luminescent at room temperature in solution and in the solid state.

Cyclic and acyclic monocyclopentadienyl fluoro and chloro titanium siloxanes have been synthesised. The fluoro complexes are cyclic, whereas acyclic chloro derivatives are accessible when using bulky cyclopentadienyl ligands. Acyclic bis(cyclopentadienyl) fluoro and chloro siloxanes of titanium, zirconium and hafnium have also been prepared. The crystal structures of two cyclic titanium derivatives [{(C5Me4Et)FTiOSiBut2O}2][triclinic, space group P, a= 9.644(3), b= 11.397(3), c= 11.822(3)A, α= 116.702(10), β= 104.507(12), γ= 98.906(8)°, Z= 1] and [{(C5H4Me)FTiOSiBut2O}2][monoclinic, space group C2/c, a= 29.75(2), b= 13.152(8), c= 22.332(11)A, β= 124.88(3)°, Z= 8] have been determined.

Unlike most anthracene derivatives and other oblong shaped aromatics, 2,3-bis(n-hexyloxy)anthracene (DHOA) crystallizes in the space group R(−3) with unit cell parameters a = b = 14.639, c = 54.435 A. The molecular packing is composed of arrays of molecular triads. By computing the interaction potential of all the molecules with one another in space group R(−3), the lowest energy structure is found to be a triad and the lowest energy layer a coplanar head-to-tail packing of these triads; most of the crystal energy is associated with the layer formation and the binding energy of the various structures is calculated to depend essentially on the non-bonded van der Waals interactions. They might prefigure the arrangement of the anthracene nuclei in the gel network nodes formed by 2,3-di-n-alkoxyanthracenes whose alkyl chains possess six or more carbon atoms.