Synthesis of functional molecular rod oligomers

Andersen, Casper S.; Gothelf, Kurt V.

doi:10.1039/b815099k

Cited by 7 publications

(5 citation statements)

References 25 publications

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“…Current interest in DPA stems from its use as a rod-like energy and electron conducting unit in conjugated polymers, − dendrimers, − and molecular photonic devices. , Moreover, photoexcitation of derivatives of DPA leads to efficient double-strand DNA cleavage and cancer cell apoptosis …”

Section: Introductionmentioning

confidence: 99%

Photophysics of Diphenylacetylene: Light from the “Dark State”

Saltiel

Kumar

2012

J. Phys. Chem. A

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A weak band at the tail of the known tolane (diphenylacetylene, DPA) fluorescence spectrum in several solvents is assigned to the forbidden 1(1)A(u) → 1(1)A(g) transition on the basis of its lifetime (∼200 ps) and its fluorescence excitation spectra. The 1(1)A(u) state, generally called the dark state, is not truly dark. We report the temperature (T) dependence of DPA fluorescence quantum yields (ϕ(f)) in methylcyclohexane (MCH) solution and the fluorescence and phosphorescence quantum yields of DPA in glassy MCH at 77 K. Significant differences between fluorescence and phosphorescence excitation spectra reveal that, in addition to the 1(1)B(1u) ← 1(1)A(g) transition, the first DPA absorption band includes a transition to another excited state, most probably the 1(1)B(2u) state, from which intersystem crossing is more efficient. The T dependence of ϕ(f) values in MCH solution is shown to be consistent with the previously reported T dependence of the lifetimes of transient DPA singlet excited state absorptions in the picosecond time scale. Transient absorption decay rate constants in hexane, methylcyclohexane and decalin as a function of T are retreated. Application of the medium enhanced barrier model shows that the medium is fully engaged with the molecular motion that is involved in the activated nonradiative decay path of the 1(1)B(1u) state. In accord with theoretical calculations and experimental observations, that process is assigned to the diabatic internal conversion of the short-lived linear fluorescent π,π* (1(1)B(1u)) state, over a low intrinsic energy barrier, to the longer lived weakly fluorescent trans-bent π,σ* (1(1)A(u)), which is the precursor of the DPA triplet state. Absorption and fluorescence measurements in several solvents show that the 1(1)B(1u)-1(1)A(g) energy gap decreases linearly with increasing medium polarizability. Our results allow a more definitive state order assignment for DPA.

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Section: Introductionmentioning

confidence: 99%

Photophysics of Diphenylacetylene: Light from the “Dark State”

Saltiel

Kumar

2012

J. Phys. Chem. A

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“…6 Model systems containing oligo(ethylene, acetylene, phenylene)-based components have been extensively investigated using various experimental methods 7 and synthetic work is ongoing. 8 When such p-conjugated systems are incorporated in solid-state devices, one important aspect from the electronic structure point of view is the nature of the coupling of the organic molecule to the electrode and the manner in which this affects charge injection into the wire. 9 In this context, properties like the ionization potential and band gap of the wire are important, and the ability to compare accurately calculated values and experimental values offers the potential to lead to a better understanding of the physical and chemical properties of conjugated polymers, [10][11][12][13] particularly in as much as ionization potentials and band gaps in the organic wire can be modified by chemical substitution in much the same fashion as Fermi levels in solids may be modified by doping.…”

Section: Introductionmentioning

confidence: 99%

Second-order perturbation theory with complete and restricted active space reference functions applied to oligomeric unsaturated hydrocarbons

Shahi

Cramer

Gagliardi

2009

Phys. Chem. Chem. Phys.

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Multiconfigurational second-order perturbation theory based on either a complete active space reference wave function (CASSCF/CASPT2) or a restricted active space reference wave function (RASSCF/RASPT2) has been applied to compute one-electron ionization potentials and vertical electronic energy differences of oligomers of length n formed from ethylene (n = 1-10), acetylene (n = 1-5), and phenylene (n = 1-3) subunits. The RASSCF/RASPT2 approach offers an accuracy similar to CASSCF/CASPT2 at significantly reduced computational expense (both methods show good agreement with experimental data where available). It is shown that RASPT2 extends the range of CASPT2-like approaches by permitting the use of larger active spaces.

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“…Both monomers (5 and 7) needed for the Sonogashira polymerization reaction were synthesized via similar pathways (Scheme 2). 18 From 1 H NMR analysis it was observed that some of the bromine atoms on the alkyl side chains were replaced by iodine during this reaction, leading to an extra triplet at 3.18 ppm (Fig. A large excess of 1,8-dibromooctane was used to prevent two-fold reaction on one alkyl chain and potassium carbonate was found to give better yields than sodium hydroxide 16 or sodium hydride (in ethanol).…”

Section: Resultsmentioning

confidence: 99%

“…Pd(PPh 3 ) 2 Cl 2 was used as the catalyst and CuI as the co-catalyst. 18 From 1 H NMR analysis it was observed that some of the bromine atoms on the alkyl side chains were replaced by iodine during this reaction, leading to an extra triplet at 3.18 ppm (Fig. S2 †).…”

Section: Polymer Chemistry Papermentioning

confidence: 99%

Synthesis of a multifunctional poly(p-phenylene ethynylene) scaffold with clickable azide-containing side chains for (bio)sensor applications

et al. 2015

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Poly(p-phenylene ethynylene) (PPE) copolymers with alternating alkoxy and azide-functionalized alkoxy side chains were efficiently synthesized via Sonogashira polymerization and the materials were fully characterized. Among the different synthetic protocols investigated, the best results were obtained when employing a pre-polymerization functionalization approach and upon implementing the azide-functionalized side chains on the diiodophenyl building block. End-capping of the conjugated polymer chains is shown to be essential for preventing side reactions. As a proof of principle, phenylacetylene is clicked in a nearly quantitative way on the polymer backbone. Furthermore, successful click-immobilization of randomly alkynylated protein A onto an azide-functionalized PPE film illustrates the potential use of these materials in a variety of (bio)sensor applications. † Electronic supplementary information (ESI) available: MALDI-TOF mass spectrum of copolymer P2a, 1 H and 13 C NMR spectra of monomers and polymers, cyclic voltammograms, and FT-IR spectra. See

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Synthesis of functional molecular rod oligomers

Cited by 7 publications

References 25 publications

Photophysics of Diphenylacetylene: Light from the “Dark State”

Photophysics of Diphenylacetylene: Light from the “Dark State”

Second-order perturbation theory with complete and restricted active space reference functions applied to oligomeric unsaturated hydrocarbons

Synthesis of a multifunctional poly(p-phenylene ethynylene) scaffold with clickable azide-containing side chains for (bio)sensor applications

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