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Beyond previously described carbo‐naphthalene and carbo‐biphenyl, a novel type of bis‐carbo‐benzenic molecules is envisaged from the stilbene parent. The synthesis, structure, spectroscopic and electrochemical properties of two such carbo‐stilbenes are described at complementary experimental and computational DFT levels. In the selected targets, the bare skeletal carbo‐mer of carbo‐stilbene is decorated by 8 or 10 phenyl groups, 0 or 2 tert‐butyl groups, and 2 n‐octyl chains, the later substituents being introduced to compensate anticipated solubility issues. As in the parent stilbene series, isomers of the phenylated carbo‐stilbenes are characterized. The cis‐ and trans‐isomers are, however, formed in almost equal amounts and could not be separated by either chromatography or crystallization. Nevertheless, due to a slow interconversion at the NMR time scale (up to 55 °C) the 1H NMR signals of both isomers of the two carbo‐stilbenes could be tentatively assigned. The calculated structure of the cis‐isomer exhibits a helical shape, consistent with the observed magnetic shielding of phenyl p‐CH nuclei residing inside the shielding cone of the facing C18 ring. The presence of the two isomers in solution also gives rise to quite broad UV‐vis absorption spectra with main bands at ca 460, 560 and 710 nm, and a significant bathochromic shift for the decaphenylated carbo‐stilbene vs the di‐tert‐butyl‐octaphenylated counterpart. Square wave voltammograms do not show any resolution of the two isomers, giving a reversible reduction wave at −0.65 or −0.58 V/SCE, and an irreversible oxidation peak at 1.11 V/SCE, those values being classical for most carbo‐benzene derivatives. Calculated NICS values (NICS(1)=−12.5±0.2 ppm) also indicate that the aromatic nature of the C18 rings is not markedly affected by the dialkynylbutatriene (DAB) connector between them. [ABSTRACT FROM AUTHOR]

Since the discovery of cisplatin in the 1960s, the search for metallo-drugs that are more efficient than platinum complexes with negligible side effects has attracted much interest. Among the other metals that have been examined for potential applications as anticancer agents is copper. The interest in copper was recently boosted by the discovery of cuproptosis, a recently evidenced form of cell death mediated by copper. However, copper is also known to induce the proliferation of cancer cells. In view of these contradictory results, there is a need to find the most suitable copper chelators, among which Schiff-based derivatives offer a wide range of possibilities. Gathering several metal complexes in a single, larger entity may provide enhanced properties. Among the nanometric objects suitable for such purpose are dendrimers, precisely engineered hyperbranched macromolecules, which are outstanding candidates for improving therapy and diagnosis. In this review article, we present an overview of the use of a particular Schiff base, namely pyridine–imine, linked to the surface of dendrimers, suitable for complexing copper, and the use of such dendrimer complexes in biology, in particular against cancers. [ABSTRACT FROM AUTHOR]

This review describes the two-photon absorption properties of dendrimers, which are arborescent three-dimensional macromolecules differing from polymers by their perfectly defined structure. The two-photon absorption process is a third order non-linear optical property that is attractive because it can be used in a wide range of applications. In this review, dendrimers that were studied for their two-photon absorption properties are first described. Then, the use of dendritic TPA chromophores for light harvesting, photopolymerization, optical power limitation, cell imaging, singlet oxygen generation, and photodynamic therapy is described. This review thus proposes an overview of the properties and possible applications of two-photon absorbing dendrimers. [ABSTRACT FROM AUTHOR]

This review describes the synthesis of polyphosphorhydrazone (PPH) dendrimers,which are highly branched macromolecules, having a phosphorus atom at each branching point. The properties of these PPH dendrimers in the field of catalysis are then described. The review is organized to illustrate in the first part how the specificities of dendrimers could contribute to green chemistry. This concerns in particular the dendritic effect that is an increased efficiency (yield, enantioselectivity, etc.) when the size of the dendrimer increases, the recovery and reuse of the dendritic catalyst, the decreased leaching, and the entrapping of nanoparticles. In a second part, some even greener approaches of catalysis with dendrimers will be displayed, such as catalysis in water, switchable catalysis, and organocatalysis (nometal used). Different types of catalytic reactions have been studied, such as Stille, Suzuki and Sonogashira couplings, Knoevenagel condensations, Michael additions, asymmetric allylic alkylations, O- and N-arylation and vinylation reactions, [2+2+2]-cycloaddition reactions, isomerization of 1-octan-3-ol, Friedel--Crafts acylations, Heck reactions, hydrogenations, hydrations, transfer hydrogenations, amination of β-dicarbonyl compounds, etc. [ABSTRACT FROM AUTHOR]

The Staudinger reaction between a phosphine and an azide, applied to phosphorus azides, has been used for the synthesis of a large variety of dendritic structures, incorporating P=N−P=X moieties (X = mainly S, but also O and N−R). Conjugation of the P=N bond with the P=X bond greatly stabilizes the P=N bond. Highly branched structures such as dendrons, dendrimers, Janus dendrimers, layered dendrimers, surface‐block dendrimers, and diverse other dendritic structures incorporating such linkage have been elaborated. Accelerated methods of synthesis of dendrimers are also based on the Staudinger reaction. A versatile reactivity was observed exclusively on the sulfur atom of P=N−P=S linkages, such as alkylation or complexation. Alkylation on S induces a weakening of the strength of the P=S bond, which can be easily cleaved to generate phosphines able to react in Staudinger reactions inside the structure of dendrimers, thus affording highly sophisticated dendritic structures. [ABSTRACT FROM AUTHOR]

In the search for carbo-benzene derivatives with sizable photoluminescent properties, e.g. with the view to measuring the two-photon absorption cross-section with the efficient TPEF method (vs. the z-scan method), a thienyl-benzothiadiazole (BTD) motif was envisaged as an intrinsic fluorophoric substituent through an acetylenic linker. A quadrupolar tetraphenyl-carbo-benzene with 2 BTD-containing substituents was synthesized from a key [6]pericyclynedione dielectrophile and 2 equiv. of a dihexylthienylbenzothiadiazolylacetylene nucleophile. Reductive aromatization of the resulting [6]pericyclynediol was found to occur in 20% yield using SnCl2 only, a quite high yield in the absence of HCl. The parent benzenic derivative was obtained by Sonogashira coupling of 1,4-diodobenzene with 2 equiv. of the same terminal alkyne, providing a new fluorophoric oligophenyleneethynylene derivative ([3]OPE) emitting at λem = 550 nm with a quantum yield of ΦF = 70%. For the highly carbon-rich carbo-benzene-BTD conjugate, the solubility provided by the four hexyl substituents allowed full characterization by 1H–13C NMR spectroscopy and voltammetry, in particular giving a very small absolute potential for a reversible reduction at E1/2 = −0.53 V/SCE. A classical UV-vis absorption spectrum was recorded, with a maximum band at λabs1 = 499 nm (ε1 = 5.79 104 L mol−1 cm−1). UV-Vis emission spectra were also recorded, showing residual intrinsic fluorescence of the functional substituents at λem = 570 nm, at a local minimum of the absorption spectrum before a secondary band at λabs2 = 612 nm (ε2 = 1.75 104 L mol−1 cm−1). Nevertheless, accurate measurements allowed the determination of the carbo-benzene's fluorescence quantum yield: ΦF = 0.3%. A short analysis of electron delocalization is provided from basic DFT calculations. [ABSTRACT FROM AUTHOR]

Azulene is stabilized by "zwitterionic aromaticity", what about its ring carbo‐mer? The greater dipole moment of the latter is oriented in the opposite direction, while providing an enhanced zwitterionic aromatic character. Comparison of local aromaticity indices for the two rings, with 5 and 7 C−C bonds in azulene or C−C2−C edges in carbo‐azulene, allows analysis of the quasi‐independent influence of size on the π‐electronic properties of these aromatic bicyclic molecules exhibiting quasi‐identical shapes and π‐resonance schemes between their common set of sp2C−H vertices. The electrostatic features of such dipolar hydrocarbons are also analyzed by comparison with their respective radical cation and anion, and with their apolar bicyclic isomer, naphthalene and carbo‐naphthalene. [ABSTRACT FROM AUTHOR]

After extensive studies of 1D and 2D skeletal carbo‐mers based on C8 π‐conjugating dialkynylbutatriene units (DABs: ∼C≡C−(R)C=C=C=C(R)−C≡C∼) bridging sp or sp2 centers in carbo‐butene, carbo‐xylylene or carbo‐benzene derivatives, 3D versions are envisaged through carbo‐barrelenes and partially reduced derivatives thereof where two or three DAB blades span a bridge between sp3 carbinol vertices or ether thereof. For R=Ph, stable representatives were synthesized through a pivotal [6]pericyclynedione, and extensively characterized by spectroscopic, electrochemical and crystallographic methods. Density functional theory calculations allow detailed analysis of structural and electronic features of the 7 Å high C26 barrel‐shaped molecules, and show that they can behave as cages for ionic species. Beyond aesthetical concerns, the results could open prospects of applications in host‐guest supramolecular chemistry and single molecule charge transport. [ABSTRACT FROM AUTHOR]

The dream to produce green, clean, and sustainable hydrogen from earth‐abundant and free resources such as seawater and sunlight is highly motivating because of the interest for desirable economical and societal applications in energy. However, it remains challenging to develop an efficient and unassisted photocatalytic device to split seawater molecules with just sunlight without any external bias. For the first time, a such novel hierarchical material has been developed, based on thin film technology that integrates TiO2 semiconductor layers, embedded gold nanoparticles, and a photosensitive carbo‐benzene layer. The design of the triptych device placing the photocatalyst in be‐to‐be increases the photoactive surface area by a factor 2. Its stability (>120 successive hours of hydrogen production and >5 days in a day/night representative alternation) and efficiency (Soler‐to‐Hydrogen 0.06%) are measured in NaCl‐salted water. The chloride ions act as hole scavengers and induce an increase of pH increasing in turn the sun‐driven hydrogen production rate. [ABSTRACT FROM AUTHOR]

carbo‐Benzene is an aromatic molecule devised by inserting C2 units within each C−C bond of the benzene molecule. By integrating the corresponding carbo‐quinoid core as bridging unit in a π‐extended tetrathiafulvalene (exTTF), it is shown that a carbo‐benzene ring can be reversibly formed by electrochemical reduction or oxidation. The so‐called carbo‐exTTF molecule was thus experimentally prepared and studied by UV–visible absorption spectroscopy and cyclic voltammetry, as well as by X‐ray crystallography and by scanning tunneling microscopy (STM) on a surface of highly oriented pyrolytic graphite (HOPG). The molecule and its oxidized and reduced forms were subjected to a computational study at the density functional theory (DFT) level, supporting carbo‐aromaticity as a driving force for the formation of the dication, radical cation, and radical anion. By allowing co‐planarity of the dithiolylidene rings and carbo‐quinoidal core, carbo‐exTTFs present a promising new class of redox‐active systems. [ABSTRACT FROM AUTHOR]

Beyond demonstration of conceptual relevance and synthetic feasibility of aryl/alkyl-substituted representatives, carbo-benzene molecules started to gain prospects of broader impact through the emergence of alkynyl derivatives. This is first illustrated by examples of diand hexaalkynyl-carbo-benzenes, a carbo-naphthalene, a carbo-biphenyl, and two carbo-terphenyls. A focus is then given to dialkynyl derivatives by reference to the peripherally C2-extruded parents. In the centrosymmetric quadrupolar series, the C2 expansion or ethynylogation effect is more particularly considered for 9H-fluoren-2-yl, tris(O-nalkyl) pyrogallyl, indol-3-yl, 4-anilinyl, and tetraphenyl-carbo-phenyl substituents on the following respective properties: two-photon absorption, chemical stability, columnar mesogenicity, on-surface photoinduced charge separation vs single-molecule conductance, and reduction potential. Topical results and prospects of application are discussed on the basis of crystallographic, spectroscopic, and electrochemical analyses vs DFT-calculated nuclear and electronic structures. For the sake of the discussion consistency, complementary experimental and computational results are disclosed in the dianilinyl series. Overall, it is shown that combined advances in strategy, protocols, and substrate scope of acetylenic synthesis remain crucial for the development of yet poorly explored but promising types of molecular materials. 1 Introduction 2 Hexaalkynyl-carbo-benzene 3 ortho-Dialkynyl-carbo-benzene 4 para-Dialkynyl-carbo-benzenes 4.1 Bistrimethylsilylethynyl-carbo-benzene 4.2 Bisfluorenylethynyl-carbo-benzene 4.3 Bistrialkoxyarylethynyl-carbo-benzenes 4.4 Bisindolylethynyl-carbo-benzene 4.5 Bisanilinylethynyl-carbo-benzene 5 Carbo-oligo(phenyleneethynylene)s 6 Conclusions. [ABSTRACT FROM AUTHOR]

Among acetylenic natural products, chiral lipidic alkynylcarbinol (LAC) metabolites, mostly extracted from marine sponges, have revealed a broad spectrum of biological activities, in particular, remarkable antitumor cytotoxicity. With reference to one of the simplest natural representatives, [(S)-eicos-(4E)-en-1-yn-3-ol], and a given cancer cell line (HCT116), combined extensive efforts in chemical synthesis (relying on the use of a large chemical toolbox) and biological analysis (in vitro tests), have provided systematic structure–activity relationships (SARs) where the initially selected four structural parameters appear as independent principal components: (i) and (ii) the sp/sp2 content and extent of the terminal and internal unsaturations adjacent to the carbinol center, (iii) the absolute configuration of the latter, (iv) the length of the n-aliphatic backbone. Two key criteria have also been established regarding the functional alkynylcarbinol pharmacophore: the alkynylcarbinol unit must be both secondary and terminal (i.e., substituted by a short ethynyl or ethenyl C2 group). This review is intended to provide a further illustration of the value of a simple rational approach for drug design, and to act as a benchmark for future optimization of LACs as antitumor agents. 1 Introduction 2 2C2-Unsaturated Pharmacophore Candidates 2.1 Alkenylalkynylcarbinols (AACs) 2.2 Dialkynylcarbinols (DACs or DACys) 2.3 Alkynylalkenylcarbinols (iso-AACs) and Dialkenylcarbinols (DACes) 2.4 Oxidation-Protected Dialkynylcarbinols and Dialkynylketones 2.5 Fluorophore-Labeled Lipidic Dialkynylcarbinols 3 C2/C3-Unsaturated Pharmacophore Candidates 3.1 Cyclopropylalkynylcarbinols (CACs) 3.2 Allenylalkynylcarbinols (AllACs) 4 C2/C4- and 3C2-Unsaturated Pharmacophore Candidates 4.1 Butadiynylalkynylcarbinols (BACs) 4.2 Trialkynylcarbinols (TACs) 5 Double-AC-Headed Pharmacophore Candidates 6 Screening on the Lipidic Chain Length 7 Conclusion [ABSTRACT FROM AUTHOR]

Abstract: Hexa‐tert‐butyl‐carbo‐benzene (C18tBu6) and three phenylated counterparts (C18tBumPh6−m; m=4, 2) have been synthesized. The peralkylated version (m=6) provides experimental access to intrinsic features of the insulated C18 core independently from the influence of π‐conjugated substituent. Over the series, structural, spectroscopic, and electrochemical properties are compared with those of the hexaphenylated reference (m=0). Anchoring tBu substituents at the C18 macrocycle is shown to enhance stability and solubility, and to dramatically modify UV/Vis absorption and redox properties. Whereas all carbo‐benzenes reported previously were obtained as dark‐reddish/greenish solids, crystals and solutions of C18tBu6 happen to be yellow (λmax=379 vs. 472 nm for C18Ph6). In comparison to C18Ph6, the reduction of C18tBu6 remains reversible, but occurs at twice as high an absolute potential (E1/2=−1.36 vs. −0.72 V). Systematic XRD analyses and DFT calculations show that the C18 ring symmetry is the nearest to D6h for m=6, which indicates a maximum geometric aromaticity. According to calculated nucleus‐independent chemical shifts (NICS), the macrocyclic magnetic aromaticity is also maximum for C18tBu6: NICS(0)=−17.2 ppm versus (−18.0±0.1) ppm for the theoretical references C18H6 and C18F6, and −13.5 ppm for C18Ph6. Accurate correlations of NICS(0) with experimentally recorded or calculated maximum UV/Vis absorption wavelengths, λmax, and chemical hardness, η=ELUMO−EHOMO, are evidenced. [ABSTRACT FROM AUTHOR]

Abstract: Ring carbo‐mers of oligo(phenylene ethynylene)s (OPEn, n=0–2), made of C2‐catenated C18carbo‐benzene rings, have been synthesized and characterized by NMR and UV‐vis spectroscopy, crystallography and voltammetry. Analyses of crystal and DFT‐optimized structures show that the C18 rings preserve their individual aromatic character according to structural and magnetic criteria (NICS indices). Carbo‐terphenyls (n=2) are reversibly reduced at ca. −0.42 V/SCE, i.e. 0.41 V more readily than the corresponding carbo‐benzene (−0.83 V/SCE), thus revealing efficient inter‐ring π‐conjugation. An accurate linear fit of E1/2red1 vs. the DFT LUMO energy suggests a notably higher value (−0.30 V/SCE) for a carbo‐quaterphenyl congener (n=3). Increase with n of the effective π‐conjugation is also evidenced by a red shift of two of the three main visible light absorption bands, all being assigned to TDDFT‐calculated excited states, one of them restricting to a HOMO→LUMO main one‐electron transition. [ABSTRACT FROM AUTHOR]

Abstract: Ring carbo‐mers of oligo(phenylene ethynylene)s (OPEn, n=0–2), made of C2‐catenated C18carbo‐benzene rings, have been synthesized and characterized by NMR and UV‐vis spectroscopy, crystallography and voltammetry. Analyses of crystal and DFT‐optimized structures show that the C18 rings preserve their individual aromatic character according to structural and magnetic criteria (NICS indices). Carbo‐terphenyls (n=2) are reversibly reduced at ca. −0.42 V/SCE, i.e. 0.41 V more readily than the corresponding carbo‐benzene (−0.83 V/SCE), thus revealing efficient inter‐ring π‐conjugation. An accurate linear fit of E1/2red1 vs. the DFT LUMO energy suggests a notably higher value (−0.30 V/SCE) for a carbo‐quaterphenyl congener (n=3). Increase with n of the effective π‐conjugation is also evidenced by a red shift of two of the three main visible light absorption bands, all being assigned to TDDFT‐calculated excited states, one of them restricting to a HOMO→LUMO main one‐electron transition. [ABSTRACT FROM AUTHOR]

Hexaalkoxy-di(phenylethynyl)-tetraphenyl-carbo-benzenes bearing six CnH2n+1 aliphatic chains (n = 12, 18) have been synthesized and characterized, including by single crystal XRD analysis. For n = 12, a liquid crystal behaviour was observed in the range of 109–130 °C. DSC, POM and PXRD analyses evidenced a rectangular columnar mesophase at 115 °C. The determined 3D lattice constants are consistent with 2D STM images of the so-called “carbo-mesogen” deposited on an HOPG surface. [ABSTRACT FROM AUTHOR]

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A ring carbo-mer of naphthalene, C32Ar8 (Ar= p- n-pentylphenyl), has been obtained as a stable blue chromophore, after a 19-step synthetic route involving methods inspired from those used in the synthesis of carbo-benzenes, or specifically devised for the present target, like a double Sonogashira-type coupling reaction. The last step is a SnCl2/HCl-mediated reduction of a decaoxy- carbo-decalin, which is prepared through successive [8+10] macrocyclization steps. Two carbo-benzene references are also described, C18Ar6 and o-C18Ar4(C≡C-Si iPr3)2. The carbo-naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of 1H nuclei of the Ar groups and on the negative value of the DFT-calculated NICS at the center of the C18 rings (−12.8 ppm). The stability and aromaticity of this smallest fused molecular fragment of α-graphyne allows prediction of the same properties for the carbon allotrope itself. [ABSTRACT FROM AUTHOR]

Since the concept of aromaticity has been proposed to be generalizable to acetylenic rods ('linear ring' of [2]annulene), p-diisopropyl- tetraphenyl-carbo-benzene (C48H34) and an indenone-fused isopropyl- triphenyloctadehydro[14]annulene (C42H26O) can be regarded as based on heptacyclic aromatic cores. The formation and X-ray crystal structures of both products are described. The latter has been obtained as a reductive rearrangement product of a transient isopropyl-pentaoxy[ 5]pericyclyne devised as a putative precursor of a carbo-fulvene target. A mechanism accounting for this peculiar transformation is proposed. Deviation from global planarity is measured by a 6° angle between the mean plane of the indenone bicycle and that of 13 atoms of the [14]annulenic macrocycle, forming dihedral angles with the local plane of the isopropyl-substituted sp2 vertex of 16° and 15°, respectively. The magnetic aromaticity of the carbo-benzene and indeno-octadehydro[ 14]annulene products is evaluated by NICS calculations. [ABSTRACT FROM AUTHOR]

The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (CC bonds for 3 a, CCCC expanders for 3 b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections σ2PA. Z-scan measurements (under NIR femtosecond excitation) indeed showed that the CC expansion results in an approximately twofold increase in the σ2PA value, from 336 to 656 GM (1 GM=10−50 cm4 s molecule−1 photon−1) at λ=800 nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of σ2PA( λi), in which λi=2 hc/ Ei, h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated σ2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z-scan results. [ABSTRACT FROM AUTHOR]

While the concept of aromaticity is being more and more precisely delineated, the category of “aromatic compounds” is being more and more expanded. This is illustrated by an introductory highlight of the various types of “aromaticity” previously invoked, and by a focus on the recently proposed “aromatic character” of the “two-membered rings” of the acetylene and butatriene molecules. This serves as a general foundation for the definition of “carbo-aromaticity”, the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic–polycyclic representatives constituting a natural family of “novel aromatic compounds”. With respect to their parent molecules, carbo-mers are constitutionally defined as “carbon-enriched”, and can also be functionally regarded as “π-electron-enriched”. This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to “pro-aromatic” congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of “molecular materials” for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite (“graphitynes”) have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results on a carbo-benzenoid fragment are finally disclosed. [ABSTRACT FROM AUTHOR]

The carbo-mer of the para-quinodimethane core is stable within in a bis(9-fluorenylidene) derivative. Oxidation of this carbo-quinoid with MnO2 in the presence of SnCl2 and ethanol affords the corresponding p-bis(9-ethoxy-fluoren-9-yl)-carbo-benzene. The latter can be in turn converted back into the carbo-quinoid by reduction with SnCl2, thus evidencing a chemical reversibility of the interconversion between a pro-aromatic carbo-quinoid and an aromatic carbo-benzene, and is reminiscent of the behavior of the benzoquinone/hydroquinone redox couple (in the red-ox opposite sense). [ABSTRACT FROM AUTHOR]

Beyond rigorous inspection of the literature, selected comments and drawings from the Nozoe Autograph Books show how concepts and targets of the chemistry of today already existed 40 years ago. This is illustrated for the chemistry of carbo-mers, which was actually unknowingly inspired by chemists of the golden age. After a personal travel through time and pages by the last author of this essay, who meets autographs by people who have been important in his career, in particular on the occasions of Nozoe's visits to France or past ISNA events, unpublished results in non-benzenoid chemistry are dedicated to Nozoe's memory. Experimental advances are first disclosed on the comparative chemistry of the three ortho, meta and para isomers of tetraphenyl- carbo-benzene C18H2Ph4, the known ortho isomer serving as a reference. The two CH vertices of these chromophores make their [6]pericyclyne precursors quite sensitive and their yields and purifications challenging to optimize. The meta isomer was, however, isolated in 18% yield, and described by NMR and UV-vis absorption spectroscopy and crystallography. The para isomer was characterized both in pure form and in a 1:1 mixture with a single isomer of its HCl adduct, including by X-ray diffraction analysis of a co-crystal showing that the interior of the C18 ring of the HCl adduct is filled by the Cl atom. Theoretical advances are then offered regarding the 'aromatic character' of a triple bond, by showing that the topological acyclic reference of acetylene is the Möbius-twisted cyclobutadiene. Acetylenoids are finally proposed as a novel class of non-benzenoid aromatics. [ABSTRACT FROM AUTHOR]