Polyene Structure Research Articles

Antifungal Activity of Disalt of Epipyrone A from Epicoccum nigrum Likely via Disrupted Fatty Acid Elongation and Sphingolipid Biosynthesis.

Multidrug-resistant fungal pathogens and antifungal drug toxicity have challenged our current ability to fight fungal infections. Therefore, there is a strong global demand for novel antifungal molecules with the distinct mode of action and specificity to service the medical and agricultural sectors. Polyenes are a class of antifungal drugs with the broadest spectrum of activity among the current antifungal drugs. Epipyrone A, a water-soluble antifungal molecule with a unique, linear polyene structure, was isolated from the fungus Epiccocum nigrum. Since small changes in a compound structure can significantly alter its cell target and mode of action, we present here a study on the antifungal mode of action of the disalt of epipyrone A (DEA) using chemical-genetic profiling, fluorescence microscopy, and metabolomics. Our results suggest the disruption of sphingolipid/fatty acid biosynthesis to be the primary mode of action of DEA, followed by the intracellular accumulation of toxic phenolic compounds, in particular p-toluic acid (4-methylbenzoic acid). Although membrane ergosterol is known to be the main cell target for polyene antifungal drugs, we found little evidence to support that is the case for DEA. Sphingolipids, on the other hand, are known for their important roles in fungal cell physiology, and their biosynthesis has been recognized as a potential fungal-specific cell target for the development of new antifungal drugs.

Cocrystal of Lutein with Improved Stability and Bioavailability.

Lutein (LT) is a natural carotenoid and is widely used for its vision protection and antioxidant activity. However, the long-chain polyene structure makes lutein sensitive to light and oxygen and poses many difficulties in the production, processing, and storage. In addition, the special chemical structure of LT leads to low solubility and bioavailability. In this study, we propose an efficient solution to address these issues. A cocrystal of LT with adipic acid (LT-APC) was obtained for the first time. The cocrystals were fully characterized. After cocrystallization, the melting point of marketed LT was increased. The chemical stability of LT was significantly improved, and the influence of impurities on stability was limited. Dissolution experiments were performed in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) and the cocrystal generated a much higher apparent solubility. To deepen insight into the mechanisms underlying the cocrystal's improved solubility, wettability tests were performed by contact angle determination and film flotation methods. The cocrystal presented better wettability than the marketed LT. Finally, pharmacokinetic studies of marketed LT and its cocrystal were conducted in rats. The results showed that the cocrystal exhibited 3.4 times higher C max and 2.2 times higher AUC at a single dose compared with marketed LT.

Effect of high-temperature thermo-oxidation on the mechanical and electrical properties of phenylethynyl-terminated polyimide/carbon fiber composite

The thermal degradation behaviors of phenylethynyl-terminated polyimide and their carbon fiber reinforced composites (CFRC) are significant to be evaluated comprehensively as their high-temperature applications are gradually expanded. It is found that ether-containing thermoset polyimide (PI) film shows unique degradation behaviors near glass transition temperature (Tg). Though the triethylamine (Et3N) chemical imidization method is applied, the PI backbone shows thermal stability at 371℃ thermo-oxidation condition and the main degradation parts site at the curing structure. More aliphatic (CC) linkages will be formed in the thermo-oxidation process and they are ascribed to the further crosslinking behaviors of polyene structure. However, the PI film shows stable mechanical properties after thermo-oxidation. Meanwhile, the formation of an amorphous carbon structure is found after thermo-oxidation treatment, which endows the composite with enhanced electrical properties. Though the micro-cracking phenomenon happens at the matrix/CF interface of composite surface and thus degrades its mechanical properties, the in-plane longitudinal and transverse conductivity of the composite perform an increase, factors of 1.13 to 2.56×104 S/m and 2.28 to 454.8 S/m, respectively. Mechanism study indicates that the formation of amorphous carbon components is caused by the structural rearrangement of the degrading polyene curing structure and becomes more in the thermo-oxidation process, not affecting the backbone integrity and mechanical stability of the PI matrix. As a result, thermo-oxidation treatment degrades the mechanical properties of the composite, whereas the formed amorphous carbon component acts as a self-growing carbon-based nano-filling structure at the PI/CF interface and enhances the electrical contact of the carbon fibers.

The Field-Effect Transistor Based on a Polyyne–Polyene Structure Obtained via PVDC Dehydrochlorination

We report on the formation of the field-effect transistor based on a polyyne–polyene structure. Polyvinylidene chloride (PVDC) drop casting and its subsequent dehydrochlorination in KOH solution allowed for the formation of porous polyyne–polyene material, which was analyzed via transmission electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, revealing the presence of sp- and sp2-hybridized chained fragments in the structure. The polyyne–polyene-based field-effect transistor showed a transconductance of 3.2 nA/V and a threshold voltage of −0.3 V. The obtained results indicate that polyyne–polyene-based transistors can be used as discrete elements of molecular electronics and that subsequent studies can be aimed toward the development of selective polyyne–polyene-based gas sensors with tunable sensitivity.

Mechanisms of formation of polyene structures in radiation-functionalized PVC-MWCNT polymer nanocomposites

Quantum-chemical modeling of the geometry of PVC molecules and the calculation of Raman scattering spectra were performed. The calculated spectra are in good agreement with the experimental ones, including the extraction of adjacent Cl atoms. The Raman spectra of PVC-MWCNT nanocomposites with various filler content with functionalization during electron irradiation with an absorption dose of 1 Mrad were obtained. It was shown that with the change of MWCNT content in irradiated samples there is a complex rearrangement of the molecular structure of PVC and conjugate sequences due to the influence of nanotubes and irradiation, as well as to the aggregation of MWCNT.

Plasticizing Effect of Camellia oleifera Seed-Oil-Based Plasticizer on PVC Material Modification

In this study, as the plasticizer, <i>Camellia oleifera</i> seed-oil-based cyclohexyl ester (COSOCE) was prepared by the reaction of cyclohexene oxide and refined <i>C. oleifera</i> seed oil (RCOSO) obtained by acidification hydrolysis after saponification. In addition, the structure of the target product was confirmed by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and Raman spectroscopy. COSOCE was used as plasticizer-modified polyvinyl chloride (PVC) membranes. The structure of the COSOCE-modified PVC membranes were characterized by Raman spectroscopy and scanning electron microscopy (SEM). The properties of the COSOCE-modified PVC membrane were characterized by contact angle measurements, universal testing machine, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results revealed that (1) The COSOCE-modified PVC membranes exhibit a good microscopic morphology. Combined with energy-dispersive X-ray spectroscopy (EDS) and contact angle measurement results, the COSOCE-modified PVC membranes are confirmed to be a hydrophilic material. (2) The modified PVC membrane with 60% COSOCE exhibited the best mechanical properties. The tensile strength reached 23.56 ± 2.94 MPa. (3) COSOCE-modified PVC material exhibited better thermal stability, with a loss rate of less than 75% at the end of the first decomposition stage. Compared with that of the dioctyl-phthalate (DOP)-modified PVC membrane, the initial decomposition temperature of PVC was increased by 1.17°C–8.17°C, and the residual rate was increased by 0.67%–5.75%. The carbon–carbon double bond in the COSOCE molecular structure can remove the free radicals generated during the degradation of PVC material and slow down the decomposition rate of PVC. In addition, the double bond can be cross-linked partially with the PVC molecular chain containing the conjugated polyene structure, thereby increasing the movement resistance of the PVC molecular chain segment. Hence, COSOCE can replace DOP as a PVC plasticizer.

Dechlorination of Polyvinyl Chloride via Solvothermal Treatment with Glycerol

Solvothermal treatment using glycerol effectively removes chlorine from polyvinyl chloride (PVC). Additive-free PVC was dechlorinated by treatment with glycerol in an autoclave at 200–240 °C. Liquid glycerol was coexistent with a red powder after the reaction at 200 °C. At reaction temperatures of 220 and 240 °C, the liquid glycerol disappeared, and carbonization proceeded to form a black powder. In this reaction, the glycerol was directly converted into glycidol. Epichlorohydrin was also produced from the glycerol via 1,3-dichloro-2-propanol as an intermediate. The PVC was converted into the polyethylene oxide structure, following the generation of the polyene structure by zip-elimination. Finally, the converted PVC was resinified by an epoxidation reaction with the glycidol and epichlorohydrin. Thus, glycerol acted as a useful reaction medium for this reaction system. The analysis of the decomposition ratio and dechlorination yield showed that the PVC was converted into solid products in high yields via chlorine release, and 30% of the glycerol was solidified by resinification at 240 °C. The effects of the additives on dechlorination were investigated using commercially available PVC sheets. Elemental analysis showed that the calorific value of the solid product dechlorinated at 240 °C was found to be higher than that of standard bituminous coal.

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile

The ambient atmosphere has the remarkable effect on the chemical reaction mechanism and the formation of characteristic chemical structures and conjugated structures for pre-oxidized polyacrylonitrile (PAN). In the present paper, fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV–vis) were used to characterize the variations of chemical reaction characteristic structures and conjugate structures of copolymerized PAN in nitrogen and air atmosphere, respectively. Combined with the multivariate reaction model proposed by the predecessors, it can be found that two main conjugated structures (conjugated polyene and conjugated aromatic heterocycle) formed during the pre-oxidation process of copolymerized PAN. In nitrogen atmosphere, the formed main structure units were the conjugated diene and conjugated double ring with 1–2 double bonds. By contrast, the formed main units in air were the conjugated diene and conjugated tricyclic with a double bond. During the whole pre-oxidation process, the maximum unit numbers of conjugated double bonds and conjugated rings were no more than four and six, respectively. Increasing the heat treatment temperature favored to form more conjugate structures than prolonging the heat treatment time. Furthermore, with the increase of heat treatment temperature or time in air, the main conjugate unit numbers had no obvious change, while the maximum unit numbers increased slightly. For the exposure in nitrogen atmosphere, the main conjugated polycyclic structure was transformed into conjugated tricyclic structure after the heat treatment at 250 °C for more than 3 h. In addition, when the heat treatment temperature and time were 280 °C for more than 4 h, the main conjugated polyene structure was transformed into conjugated triene, and the maximum conjugated unit numbers increased slightly.

Excited state relaxation in cationic pentamethine cyanines studied by time-resolved spectroscopy

In this work, we examined the nature and pathways of electronic excitation relaxation at low temperature in cationic pentamethine pyrylocyanine dye, which in the ground state is characterized by symmetric and non-symmetric localization of cationic charge on the carbon chain between the terminal groups. The carbon chain in such symmetric and non-symmetric charge localizations is close to polymethine and polyene conformations, respectively. The effect of symmetry breaking during the two-way transition polymethine – polyene in the optically excited state on the electronic properties of dyes is considered. Combined quantum-chemical calculations and time-resolved spectral measurements allowed us to characterize the symmetric and non-symmetric structures in the ground and excited states with specific peaks of transitions and lifetimes. The features of the polymethine structure of the dye are attributed to large-radius polaron formation, whereas for the polyene structures the model of excitons formed on the double bonds of the carbon chain can be used to analyze the relaxation pathways. The energy diagram model for relaxation pathways of optically excited electronic states has been proposed. The proposed model can be characteristic for pentamethine cyanine dyes with the symmetric and non-symmetric distribution of cationic charge at the carbon chain between the terminal groups in the ground and excited states.

DFT study of Raman spectra of polyenes and ß-carotene: Dependence on length of polyene chain and isomer type

We carried out calculations of non-resonance Raman spectra of ß-carotene and polyenes CH2(CHCH)n-2CHCH2 using the density functional theory (DFT). We revealed that the peak positions and intensities of the CC and CC stretching bands depend on length of the polyene chain and type of the isomer. Our experimental non-resonance Raman spectra of ß-carotene powder match well the DFT-simulated Raman spectrum of ß-carotene in the all-trans form. The peak positions and relative intensities of the CC and CC stretching bands of ß-carotene turned out to be similar in the resonance and non-resonance Raman spectra. An increase in the number of conjugated double bonds (n = 3–30) in a polyene structure results in a monotonous shift of the positions of the most intense CC and CC bands towards lower wavenumbers with an increase in the band intensities. An increase in the isomer number results in the monotonous decrease of the CC stretching band intensity for polyenes with 9, 10, 11, 15 and 24 double bonds. An increase in the isomer number inhomogeneously influences the form, position and intensity of the CC stretching band.

Construction and Properties of Donor-Acceptor Stenhouse Adducts on Gold Surfaces.

The construction of a donor–acceptor Stenhouse adduct molecular layer on a gold surface is presented. To avoid the incompatibility of the thiol surface-binding group with the donor–acceptor polyene structure of the switch, an interfacial reaction approach was followed. Poly(dopamine)-supported gold nanoparticles on quartz slides were chosen as substrates, which was expected to facilitate both the interfacial reaction and the switching process by providing favorable steric conditions due to the curved particle surface. The reaction between the surface-bound donor half and the CF3-isoxazolone-based acceptor half was proved to be successful by X-ray photoelectron spectroscopy (XPS). However, UV–vis measurements suggested that a closed, cyclopentenone-containing structure of the switch formed on the surface irreversibly. Analysis of the wetting behavior of the surface revealed spontaneous water spreading that could be associated with conformational changes of the closed isomer.

Thermal dehydrochlorination of pure PVC polymer: Part I—thermal degradation kinetics by thermogravimetric analysis

AbstractThermal degradation of PVC occurs in two stages, with each stage subdivided into two substages. The first refers to the dehydrochlorination, where hydrochloric acid is formed, and giving polyene structures. Hitherto, the degradation mechanism and action of hydrochloric acid as a catalyst during the dehydrochlorination stage are poorly known. Recently, the importance of the tacticity has gained attention for its influence on the dehydrochlorination mechanism. The present work focused on the dehydrochlorination stage, studying the molecular structure by FTIR analysis and the kinetic parameters by TGA analysis in Nitrogen atmosphere, based on three mathematical methods: Friedman, Kissinger, and Flynn‐Wall‐Ozawa. The sample was a pure homopolymer obtained by suspension polymerization. The dehydrochlorination kinetics follows a first order reaction model and occurs by nucleation and growth. The dehydrochlorination begins with the loss of very labile chlorine atoms present in defective and isotactic molecular segments. The formed HCl acts as a catalyst in the degradation. Following 40% conversion, a drop in Ea is observed. After that, chlorine atoms present in syndiotactic and atactic sequences, are released and, added to the large number of polyene chain sequences, and an increase in Ea is observed up to 60% conversion, where the dehydrochlorination stage is concluded.

Enhanced alteration of poly(vinyl chloride) microplastics by hydrated electrons derived from indole-3-acetic acid assisted by a common cationic surfactant

In this study, a new photo-irradiated reductive dechlorination pathway and the underlying transformation mechanism are described for poly(vinyl chloride) microplastics (PVC-MPs). PVC-MPs underwent photo-reductive dechlorination process with the release of chloride ions. This reaction could be facilitated in the presence of indole-3-acetic acid (IAA) and hexadecyltrimethylammonium bromide (CTAB) under neutral pH and simulated sunlight irradiation conditions. Electrostatic interaction between IAA and CTAB produced neutral IAA/CTAB complex, which might account for the enhanced adsorption of IAA on PVC powders. Upon photo-irradiation, the adsorbed IAA was excited to generate hydrated electrons (eaq−), which could pass through a shorter distance to PVC-MP surface than that derived from homogeneous IAA molecules in aqueous solution. Transient spectra of laser flash photolysis provided direct evidence for the generation of eaq−, which supported the proposed dechlorination mechanism. Based on the results of attenuated total reflectance/Fourier transform infrared (ATR/FTIR) and Raman spectra, C-Cl bond cleavage and polyene formation were involved in the structural transformation of PVC-MPs. Due to the hydrophobic effects and π-π interactions between aromatic rings and polyene structures in PVC-MP surface, the PVC-MP powders irradiated in the presence of IAA/CTAB showed an enhanced sorption for both hydrophobic and hydrophilic aromatic chemicals.

Fabrication of Yolk-Shell Silicon@Carbon Anode Via Iodination Treatment

As the demand for lithium ion batteries (LIBs) with high energy density increases, silicon has attracted great attention as a next-generation anode material due to its high theoretical capacity of 4200mAh/g. However, silicon has been suffered from poor cycleability due to a large volume change during the lithiation process. To tackle this critical problem, some methods have been used, such as nano-sized silicon, porous silicon, and a hollow carbon/silicon composite. However, nano-sized silicon is expensive for commercialization. In addition, the harmful hydrogen fluoride (HF) acid is commonly used to etch silicon oxides for porous structure. In this study, a yolk-shell structure with a space between the carbon shell and micro-sized silicon was made without HF. The poly(vinyl alcohol) (PVA) coated silicon was treated with an iodine followed by stabilization at 200 oC. The iodination process converts the chemical structure of PVA to polyene structure and enhances the carbon yield. The yolk-shell structure was formed by the eliminating an untreated PVA layer during the carbonization process. The prepared yolk-shell silicon/carbon composite worked well as an anode electrode and showed a high initial discharge capacity of 3266 mAh/g and maintained 1700 mAh/g until 200 cycles.

Epoxy resins with high heat resistance and flame retardancy via a new process

To develop highly heat‐resistant and flame‐retardant epoxy resins, the curing behavior of an epoxy resin and the properties of the resulting cured product were investigated using two compounds as curing agents, an acid anhydride containing a phenylethynylcarbonyl group and an imide compound with a phenylethynylcarbonyl group at both ends. The results indicated that reaction between the acid anhydride group and the epoxy group first proceeded at about 150°C to 170°C, followed by reaction between the phenylethynylcarbonyl groups at about 250°C to 300°C. The reaction between the acid anhydride and the epoxy group proceeded more efficiently in the presence of a small amount of the imide compound. The resulting product exhibited very good heat resistance and flame retardancy. The crosslink density was increased by polymerization of the phenylethynylcarbonyl group, and the resulting polyene structure and intramolecular imide skeleton strengthened intermolecular interactions, likely due to the limited freedom of movement of the molecular chains.

Synthesis of Symmetrical and Nonsymmetrical Polyenes by Iterative and Bidirectional Palladium-Catalyzed Cross-Coupling Reactions.

Bifunctional unsaturated reagents designed to undergo palladium-catalyzed cross-coupling reactions with complementary polyenyl connective fragments are highly useful for the undoubtedly challenging synthesis of polyenes. The current toolkit of building blocks for the bidirectional formation of Csp2 -Csp2 single bonds of polyenes includes homo-bisfunctionalized reagents with equal or unequal reactivity (due to steric and/or electronic factors), and hetero-bisfunctionalized counterparts containing either two different nucleophiles, two electrophiles or one of these functionalities and a latent nucleophile that can be unmasked when desired. The combination of these bifunctional linchpin reagents using tactics that modulate the reactivity of each terminus in order to achieve the required connection have streamlined the synthesis of polyenes of great complexity using (iterative) cross-coupling methods for Csp2 -Csp2 bond formation. Reaction conditions for the Pd-catalyzed cross-coupling reactions are mild and functional-group-tolerant, and therefore these protocols allow to construct the polyene structures using shorter unsaturated reactants with the desired geometries, since in general the products preserve the stereochemical information of the connected cross-coupling partners.

Structural basis for selectivity in a highly reducing type II polyketide synthase.

In type II polyketide synthases (PKSs), the ketosynthase-chain length factor (KS-CLF) complex catalyzes polyketide chain elongation with the acyl carrier protein (ACP). Highly reducing type II PKSs, represented by IgaPKS, produce polyene structures instead of the well-known aromatic skeletons. Here, we report the crystal structures of the Iga11-Iga12 (KS-CLF) heterodimer and the covalently cross-linked Iga10=Iga11-Iga12 (ACP=KS-CLF) tripartite complex. The latter structure revealed the molecular basis of the interaction between Iga10 and Iga11-Iga12, which differs from that between the ACP and KS of Escherichia coli fatty acid synthase. Furthermore, the reaction pocket structure and site-directed mutagenesis revealed that the negative charge of Asp 113 of Iga11 prevents further condensation using a β-ketoacyl product as a substrate, which distinguishes IgaPKS from typical type II PKSs. This work will facilitate the future rational design of PKSs.

A high-efficiency and low-temperature subcritical water dechlorination strategy of polyvinyl chloride using coal fly ash (CFA) and coal gangue (CG) as enhancers

In this study, a high-efficiency and low-temperature subcritical water (SubCW) method was proposed for the polyvinyl chloride (PVC) dechlorination using coal fly ash (CFA) and coal gangue (CG) as enhancers. The aim of this work is to evaluate the removal efficiency of chlorine from the PVC waste in the SubCW-CFA/CG process and study the enhancement mechanism of CFA/CG on the dechlorination of PVC. The effective dechlorination temperature can be reduced to 220 °C by using the SubCW-CFA/CG process. The dechlorination efficiency of SubCW-CFA/CG was much higher than that of the reported methods at 200 °C and 220 °C. The optimal processing conditions of SubCW-CFA/CG were as follows: temperature of 220 °C, residence time of 60 min, CFA/CG additive amount of 0.4 g, and solid-to-liquid ratio of 1:30 g/mL. Under the optimal parameters, the chlorine removal efficiency of PVC reached 96% and 97.34% in the SubCW-CFA and SubCW-CG process, respectively. FT-IR and elemental analysis were used to analyze the dechlorination mechanism of PVC. The dechlorination mechanism contains two pathways in the SubCW-CFA/CG process: direct dehydrochlorination and hydroxyl substitution. The direct dehydrochlorination resulted in the generation of polyene structure, and the hydroxyl substitution of C–Cl induced the formation of the stable structure of CO in the SubCW-CFA/CG treatment of PVC. The proposed SubCW-CFA/CG process is believed to be an efficient strategy for the PVC dechlorination at the temperature below 220 °C.

THE CHEMISTRY AND BIOLOGY OF LYCOPENE : ANTIOXIDANT FOR HUMAN HEALTH

More than 600 carotenoids are known to be naturally occurring. These predominantly colourful molecules, found in plants, fungi and bacteria undergoing photosynthesis, are widespread in vegetables and fruits. Carotenoids are divided into two main groups. Of them, the highly unsaturated hydrocarbons consisting of lycopene, α-, β-, and γ-carotene build the first group, whereas xanthophylls, such as β-cryptoxanthin, lutein and zeaxanthin are considered as the second big carotenoid group. Lycopene, a representative of the hydrocarbon carotenoids with the molecular formula of C40H56, has an acyclic open-chain structure consisting of 13 double-bonds. Two of them are non-conjugated, whereas eleven are conjugated double bonds, thereby building a chromatophore. This distinctive conjugated polyene structure accounts for the ruby colour and the antioxidant properties of lycopene. It has a distinct lipophilic character, which makes it nearly insoluble in ethanol, methanol and water. Due to its acyclic structure and the absence of a β-ionone ring, there is no pro-vitamin A activity to be found in lycopene, which is the reason for its differing biochemistry, as compared to α- and β-carotene. Due to its polyene-structure, providing an electron-rich system, lycopene is an eligible target for electrophilic reagents. Thus, it shows an extreme reactivity towards oxygen and free radicals. Lycopene is known to be the most potent oxygen quenching reagent among carotenoids, and furthermore, it provides the ability to intervene in reactions initiated by free radicals, like OH−· or peroxy radicals. Its excellent anti-oxidant properties are most likely the basis for its preventive role towards cancer and other chronic diseases. However, the lycopene concentration in fresh fruits and vegetables shows a great variability, depending on seasonal environmental conditions, geographic location, climatic situation, species and maturity which may be taken as indices for the best sowing season, place, species/varieties to be planted and date/time of harvest. The vegetables and fruits thus obtained would be rich in lycopene content, which in turn would have a major beneficial impact on human health.

Carbon-Bridged Oligo(phenylene vinylene)s: A de Novo Designed, Flat, Rigid, and Stable π-Conjugated System.

The modern history of conducting organic systems started with a fortuitous error in 1967 on acetylene polymerization, followed by a rational discovery in 1976 on the effects of doping that generates a polaron and, hence, dramatically increases conductivity. Not unexpectedly, however, the prototypical polyacetylene suffers many problems, including C-C single bond rotation, short effective conjugation length, radiationless deactivation, and instability of the polarons. Several strategies have been put in place to solve these problems. An early approach relied on partial rigidification of the polyene structure by conversion into polymers with thiophene, pyrrole, and benzene linkages. An oligo(phenylene vinylene) (OPV) is an all-carbon analogue of polyacetylene, where every other diene unit in the polyene chain is converted to a benzene unit, still leaving many C-C single bonds freely rotating in the molecule. We considered adding additional carbon bridges to rigidify the OPV skeleton entirely to create a carbon-bridged OPV (COPV). Making such a compound was an obvious challenge. This Account describes the authors' efforts to design and synthesize a series of COPV molecules, where the benzene rings in OPV are bridged by sp3 carbon atoms to form a bicyclo[3.3.0]octatriene framework bearing a tetrasubstituted olefin at the ring fusion. This olefinic bond is so strained that it resists further deformation or conversion to sp3 centers, and hence, it is chemically stable despite the strain. The sp3 carbon bridges can bear organic side chains that hinder intermolecular interactions, rendering the excited states stable and long-lived even in the solid state. They also increase solubility, a common problem among rigid molecular systems. With these structural features, the COPV molecules were found to be well behaved both at a single-molecule level and as a bulk material. We reported in 2009 a method for the synthesis of COPVs and have, since then, reported their structures and physicochemical properties, including basic photophysical properties of neutral and charged derivatives, thermal and photostability, and fast electron transfer. These properties have rendered the COPV molecules useful for electronic and photonic research, for example, lasers, solar cells, and molecular wire applications. Noteworthy discoveries in the area connecting chemistry and physics include inelastic tunneling and long-range resonance tunneling at ambient temperature, which were previously observed only for organic molecular wires placed under cryogenic conditions. Given the ready availability of the COPV skeleton bearing a wide variety of substituents, this class of molecules will serve as versatile building blocks for fundamental and applied research on physicochemical and materials chemistry.