Nanosized Gradient π-Conjugated Thienylethynylene Dendrimers for Light Harvesting: Synthesis and Properties

From truxenes to heterotruxenes: playing with heteroatoms and the symmetry of molecules

As a result of the modification of truxene, we can change the electronic structure or create multidimensional materials. Thus, the use of truxenes is very wide.

Efficient synthesis of 5-oxatruxene and the unusual influence of oxygen heteroatom on its physico-chemical properties

5-Oxatruxene presents new quality among the truxenes. It is a promising compound for the new class of optoelectronic materials.

Separation performance of a large π-conjugated truxene-based dendrimer as stationary phase for gas chromatography

High-resolution performance of a π-conjugated truxene-based dendrimer as the stationary phase for gas chromatographic separations.

Synthesis and photophysical properties of C3-symmetric tris(pyridyl)truxene scaffolds of Ru(ii) and Re(i)

Facial Ru(ii)- and Re(i)-complexes of a novel face-capping tris(pyridyl)truxene ligand were synthesised and characterised by various analytical techniques including single crystal XRD. The Ru(ii) complex exhibits unusual green phosphorescence with a long excited-state lifetime.

Very fast singlet and triplet energy transfers in a tri-chromophoric porphyrin dyad aided by the truxene platform

A trichromophoric dyad composed of an octa-β-alkyl-palladium(II)porphyrin (donor) and two tri-meso-aryl-zinc(II)porphyrins (acceptors) held by a truxene spacer exhibits very fast rates for triplet energy transfers at 77 (kET(T1) = 1.63 × 108 s-1) and 298 K (kET(T1) = 3.44 × 108 s-1), whereas the corresponding singlet energy transfer rates, kET(S1) = 3.9 × 1010 s-1 (77 K) and kET(S1) = 6.0 × 1010 s-1 (298 K), are also considered fast. The interpretation for these results is that the energy transfer processes proceed via a through bond Dexter mechanism (i.e. double electron exchange) supported by comparison with literature data and evidence for a moderate MO coupling between the donor and acceptor chromophores in the frontier MOs.

Truxene: a promising scaffold for future materials

Truxene (10,15-dihydro-5H-diindeno[1,2-a;1′,2′-c]fluorene), which is a heptacyclic polyarene structure, has attracted a great deal of interest due to its exceptional solubility, high thermal stability and ease with which it may be modified.

Singlet and triplet energy transfers in tetra-(meso-truxene)zinc(II)- and tetra-(meso-tritruxene)zinc(II) porphyrin and porphyrin-free base dendrimers

The synthesis, optical properties, and energy transfer features of four dendrimers composed of meso-tetrasubstituted zinc(II) porphyrin (ZnP) or a free base (P) central core, where the substituents are four truxene (Tru) or four tritruxene dendrons (TriTru), TruP, TriTruP, TruZnP, and TriTruZnP, are reported. Selective excitation of the truxene donors results in a photoinduced singlet energy transfer from the truxenes to the porphyrin acceptor. The rates for singlet energy transfer (k(ET)), evaluated from the change in the fluorescence lifetime of the donors (Tru and TriTru) in the presence and absence of the acceptor (P or ZnP) for TruP, TruZnP, TriTruP, and TriTruZnP, are 5.9, 1.2, 0.87, and 0.74 (ns)(-1) at 298 K and 2.6, 2.6, 2.7, and 1.2 (ns)(-1) at 77 K, respectively. A slow triplet-triplet energy transfer from truxene to porphyrin cores in glassy 2MeTHF at 77 K is also reported with rates of 1.3 × 10(3) and 0.10 × 10(2) s(-1) for TruZnP and TriTruZnP, respectively. If the Dexter mechanism for the triplet energy transfers is considered, these slow rates are easily explained by a poor orbital overlap between the truxene and porphyrin π systems. The fluorescence quantum yields (Φ(F)) are 0.20 and 0.16 for TruP and TriTruP and 0.08 and 0.10 for TruZnP and TriTruZnP, respectively at 298 K. At 298 K, a phosphorescence from TruZnP at 795 nm was also observed and is associated with the ZnP chromophore.

Solution-processed bulk-heterojunction photovoltaic cells based on dendritic and star-shaped D-pi-A organic dyes

A series of D-pi-A organic dendritic and star-shaped molecules based on three various chromophores (i.e., the truxene nodes, triphenylamine moieties as the donor, and benzothiadiazole chromophore as the acceptor) and their corresponding model compounds are facilely developed. Their photophysical and electrochemical properties are investigated in detail by UV/Vis absorption and photoluminescent spectroscopy, and cyclic voltammetry. By changing the various conjugated spacers (i.e., single bond, double bond, and triple bond) among the three chromophores of dendritic series, their photophysical properties (that is, the one-photon absorption range and two-photon absorption cross-section values) are effectively modulated. All D-pi-A conjugated oligomers show a broad and strong absorption band from 250 to 700 nm in thin films. Solution-processed bulk-heterojunction photovoltaic devices using our oligomer as donor and PCBM as acceptor are fabricated and measured. The power conversion efficiency of the devices based on our oligomers continuously increases from DBTTr to TrTD2A as a result of an increasing relative absorption intensity in longer wavelength region by changing the donor-acceptor ratio and conjugated spacers between the donor and acceptor. The power conversion efficiency of the devices based on TrTD2A was 0.54% under the illumination of AM 1.5 and 100 mW cm(-2), which is the highest value recorded based on D-pi-A conjugated oligomers containing triphenylamine moieties and benzothiadiazole chromophores with truxene to date.

A mechanically interlocked [3]rotaxane as a light-harvesting antenna: synthesis, characterization, and intramolecular energy transfer

A mechanically interlocked light-harvesting system [3]rotaxane A has been synthesized in high yield through Cu(I)-catalyzed azide-alkyne cycloaddition; the hexyl-substituted truxene units are introduced into the wheels as donors and an oligo(para-phenylenevinylene) (OPV) unit into the axis as the acceptor. The structure and the purity of [3]rotaxane A were confirmed by (1)H and (13)C NMR spectroscopy and ESI HRMS. The azide-alkyne cycloaddition is demonstrated to be an efficient stoppering method in the synthesis of the rotaxane containing dibenzo[24]crown-8 and dibenzyl ammonium units. Detailed steady-state UV/Vis absorption, photoluminescent, and time-resolved fluorescence spectroscopy were performed to investigate the photophysical properties of [3]rotaxane A and its reference compounds in solution and as thin films. Even in dilute solution, efficient energy transfer from the truxene-functionalized wheels to the OPV-based axis, through the dibenzo[24]crown-8 and dibenzyl ammonium interaction, is observed in [3]rotaxane A. The unique topology of [3]rotaxane A not only efficiently promotes the intramolecular energy-transfer process, but also prevents intermolecular aggregation in the solid state. The new antenna system opens up the possibility of controllable light-harvesting molecular machines or other optoelectronic devices on the nanometer scale.

Dendronlike main-chain nonlinear optical (NLO) polyurethanes constructed from "H"-type chromophores: synthesis and NLO properties

For the first time, a series of dendronlike main-chain polyurethanes have been successfully designed and synthesized, in which different isolation groups with different sizes were introduced to modify the subtle structure of the used "H"-type chromophores, according the concept of "suitable isolation groups". Thanks to the advantages of "H"-type chromophores and the introduced suitable isolation group, all of the polymers demonstrated large NLO effects, good processability, improved optical transparency, and thermal stability. The obtained experimental results indicated that the utilization of "H"-type chromophores might be a promising choice to efficiently translate the large beta values of the organic chromophores into high macroscopic NLO activities of polymers.

Large Rigid Blue-Emitting π-Conjugated Stilbenoid-Based Dendrimers: Synthesis and Properties

Two large pi-conjugated dendrimers (G0 and G1) employing the stilbenoid moiety as the bridge unit have been developed through the Suzuki and the Horner-Wadsworth-Emmons reactions. The molecular weight of G1 is 10 973 Da. Both G0 and G1 have good fluorescence quantum yields and exhibit similar absorption and emission behaviors in solutions and in thin films. They emit strong blue fluorescence in films under the irradiation of UV light.