Phenanthrene Unit Research Articles

Phenanthrene Appending Ruthenium Complexes: DNA Binding, Molecular Docking, TDDFT Calculation, and Photocytoxicity In Vitro

ABSTRACTPhotodynamic therapy (PDT) has been an effective tumor treatment to reduce the side effects of chemotherapy. Herein, we described the synthesis of two Ru (II) complexes by introducing a phenanthrene unit and their photocytotoxicity. Ru1 and Ru2 displayed high DNA affinities by intercalation. Under light, two complexes produced high singlet oxygen (1O2) quantum yields and cleaved DNA efficiently. Both high DNA affinities and 1O2 quantum yields of two complexes resulted in obvious photocytotoxicity towards Hela, A549, and A375 cells. Furthermore, low dark cytotoxicity was also observed for two complexes, which may promote them to act as potential PDT agents. TDDFT (Time‐dependent density functional theory) calculations also demonstrated two complexes that might display the PDT activities via 1O2 photogeneration.

Synthesis of (±)-Angustatin A: Assembly of the Phenanthrene Moiety Despite Increasing Ring Strain.

The synthesis of (±)-angustatin A, a phenanthrene-containing cyclophane that possesses conformational chirality, is reported. Key steps include a Pd-catalyzed Negishi coupling to assemble the necessary terphenyl intermediate, its closure into a 14-membered macrocycle via a catalytic-in-phosphine Wittig olefination, and finally a Pt-catalyzed alkyne hydroarylation, which is able to assemble the phenanthrene unit despite the thermodynamic cost of significantly bending arene A from the ideal plane.

Expanded [2,1][n]Carbohelicenes with 15- and 17-Benzene Rings.

Expanded carbohelicenes with structures fused to 15- and 17-benzene were successfully synthesized. Establishing a new synthetic strategy is crucial to realize the development of longer expanded [2,1][n]helicenes with a kekulene-like projection drawing structure. This article describes the sequential integration of the π-elongating Wittig reaction of functionalized phenanthrene units and ring-fusing Yamamoto coupling for the synthesis of [2,1][15]helicenes and [2,1][17]helicenes. X-ray crystallographic structures, photophysical properties, and density functional theory (DFT) calculations revealed the unique characteristics of the synthesized expanded helicenes. Furthermore, because of the high enantiomerization barrier derived from a wide-range intrahelix π-π interaction, the optical resolution of [2,1][17]helicene was successfully achieved, and chiroptical properties such as circular dichroism and circularly polarized luminescence were elucidated for the first time as enantiomers of pristine [2,1][n]helicene core.

Pd and Pt metal atoms as electron donors in σ-hole bonded complexes.

Quantum calculations provide a systematic assessment of the ability of Group 10 transition metals M = Pd and Pt to act as an electron donor within the context of pnicogen, chalcogen, and halogen bonds. These M atoms are coordinated in a square planar geometry, attached to two N atoms of a modified phenanthrene unit, as well as two ligand atoms Cl, Br, or I. As the Lewis acid, a series of AFn molecules were chosen, which could form a pnicogen bond (A = P, As, Sb), chalcogen bond (A = S, Se, Te) or halogen bond (A = Cl, Br, I) with M. These noncovalent bonds are fairly strong, varying between 6 and 20 kcal mol-1, with the occupied dz2 orbital of M acting as the origin of charge transferred to the acid. Pt forms somewhat stronger bonds than Pd, and the bond strength rises with the size of the A atom of the acid. Within the context of smaller A atoms, the bond strength rises in the order pnicogen < chalcogen < halogen, but this distinction vanishes for the fifth-row A atoms. The nature of the ligand atoms on M has little bearing on the bond strength. Based on the Harmonic Oscillator Model of Aromaticity (HOMA) index, the ZB, YB and XB bonds were shown to have only a subtle effect on the ring electronic structures.

Phosphorescence emission from spatial stacks of phenanthrene units in oligo(9,10-phenanthrene)s.

The covalent linkage of phenanthrene units at 9 and 10 positions resulted in a broadening of the absorption band and a red-shift of the fluorescence band in ethanol compared with its monomer. Spatial stacking of phenanthrene units also altered the spectral shape of phosphorescence emission, and the oligomer film emitted phosphorescence at room temperature.

Enhanced Optical Properties of Azaborole Helicenes by Lateral and Helical Extension.

The synthesis and characterization of laterally extended azabora[5]-, -[6]- and -[7]helicenes, assembled from N-heteroaromatic and dibenzo[g,p]chrysene building blocks is described. Formally, the π-conjugated systems of the pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds with large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) and dissymmetry factors (glum ). The beneficial effect on optical properties was also observed for helical elongation. The combined contributions of lateral and helical extensions resulted in a compound showing green emission with Φ of 0.31 and |glum | of 2.2×10-3 , highest within the series of π-extended azaborahelicenes and superior to emission intensity and chiroptical response of its non-extended congener. This study shows that helical and lateral extensions of π-conjugated systems are viable strategies to improve features of azaborole helicenes. In addition, single crystal X-ray analysis of configurationally stable [6]- and -[7]helicenes was used to provide insight into their packing arrangements.

Monte Carlo simulation of the surface-assisted self-assembly of metal-organic precursors comprising phenanthrene building blocks

Surface-assisted fabrication of carbon-based covalent architectures has been a promising pathway to low-dimensional materials with special physicochemical properties and functions. In this contribution, the Monte Carlo simulation method was used to predict the formation of metal-organic precursors preceding the covalent Ullmann coupling of halogenated phenanthrene monomers. To that end, the coarse-grained model of adsorbing (111) surface, phenanthrene molecules and linking adatoms was proposed, in which the monomers were equipped with active centers providing directional metal-linker interactions. The simulations performed for various intramolecular distributions of active centers in the phenanthrene unit (corresponding to halogen positions) resulted in diverse metal-organic superstructures, including chains, ring oligomers, triangular and windmill trimers, ladders, and periodic and aperiodic networks. For those molecules which were chiral in 2D the corresponding calculations in enantiopure and racemic overlayers were also carried out. These simulations resulted in characteristic examples of both advantageous and adverse effect of the opposite enantiomer on the ordering in racemic systems. Our theoretical findings provided some hints on how to halogenate monomeric phenanthrene units to create polymeric architectures with presumed structural features, such as topology, periodicity, connectivity, ramification and porosity.

Known or Never before Identified Phenanthrenes: Where It Is Possible to Isolate Them and Why.

The secondary metabolites of plant origin belong to different and numerous classes of organic compounds. One of these is that of dimeric phenanthrenes, symmetrical or not, characterized by a series of interesting biological activities. Of these compounds, 37 have been isolated since 1988, from only five plant families. Considering each dimer comprises two phenanthrenes and starting from the hypothesis that each dimer is obtained through a biosynthetic mechanism that involves the coupling of the corresponding radicals of the individual phenanthrene units, it is possible to identify 29 phenanthrenes, of which 6 not yet isolated. It is possible to establish that 16 known phenanthrenes can be isolated from 14 different plant species, just as 6 new phenanthrenes can be isolated from 6 different plant species. This would allow a targeted analysis of a few natural extracts from specific plant sources to identify known or new molecules, with potential and/or specific biological activities.

Synthesis of Redox-Active Photochromic Phenanthrene Derivatives.

A phenanthrene unit has been functionalized by several methylthiophene units in order to bring it a photochromic behavior. These compounds were characterized by NMR, absorption and emission spectroscopies, theoretical calculations as well as cyclic voltammetry. The association of a phenanthrene group with a photochromic center could open the door to a new generation of organic field-effect transistors.

Extended porphyrinoid chromophores: heteroporphyrins fused to phenanthrene and acenaphthylene

Fusion of aromatic subunits onto porphyrin chromophores produces variable results and in some cases only minor bathochromic shifts are observed. In order to extend these observations, a series of oxa-, thia- and selenaporphyrins with fused acenaphthylene or phenanthrene units have been synthesized. Phenanthro[5,6-b]porphyrins were previously prepared via conventional ‘2 + 2’ MacDonald condensations, but a more versatile ‘3 + 1’ synthesis is now reported. Phenanthrotripyrranes reacted with a pyrrole dialdehyde in the presence of trifluoroacetic acid, followed by an oxidation step, to give phenanthroporphyrins. However, this chemistry initially gave products that were contaminated with isomeric impurities. Fortunately, good yields of isomerically pure phenanthroporphyrins were obtained when the reactions were carried out under relatively concentrated conditions, and a diphenanthroporphyrin was also obtained using this strategy. An alternative ‘3 + 1’ synthesis was performed where a phenanthropyrrole dialdehyde was condensed with a tripyrrane and this also afforded a phenanthroporphyrin in good yields. Furan, thiophene and selenophene dialdehydes similarly reacted with phenanthro- and acenaphthotripyrranes to give a series of heteroporphyrins with fused phenanthrene and acenaphthylene rings. All of these porphyrinoids retained highly diatropic characteristics. As is the case for tetrapyrrolic porphyrins, the presence of a fused acenaphthylene unit leads to highly modified UV–vis spectra with multiple Soret bands and relatively strong Q bands above 650 nm. However, the longest wavelength absorptions for the acenaphthylene series were only red shifted by 12–15 nm compared to the phenanthrene-fused heteroporphyrin series, which is a somewhat reduced effect compared to previously reported phenanthroporphyrins and acenaphthoporphyrins. Nevertheless, the combined effects of core modification and acenaphthylene ring fusion affords potentially valuable strongly red shifted absorption bands between 677 and 684 nm.

Synthesis and photoluminescence properties of fluorine‐containing poly(phenylene vinylene) bearing hexafluorocyclopentene‐fused phenanthrene unit

AbstractThe intramolecular oxidative photocyclization of 1,2‐diarylhexafluorocyclopentene (1) under light irradiation (λ = 365 nm) provided hexafluorocyclopentene‐fused phenanthrene with formyl groups (2) in moderate yield. The copolymerization of 2 with tetraethyl(2,5‐bis(dodecyloxy)‐1,4‐phenylene)bis(methylene)diphosphonate by the Horner–Wadsworth–Emmons reaction gave a fluorine‐containing poly(phenylene vinylene), Polymer‐2, in 41% yield. For comparison, a diphenylethene‐type copolymer, Polymer‐1, was also prepared analogously. The number‐average molecular weights of Polymer‐1 and Polymer‐2 were 8900 and 3300 g mol−1, respectively. The copolymers showed high thermal stability, as revealed by their thermogravimetric analysis. UV–visible spectra of the copolymers in CHCl3 showed π–π* transition peaks at around 420 nm, and the peaks shifted to longer wavelengths by ca 10 nm for samples in film form. The photoluminescence spectra of Polymer‐1 and Polymer‐2 exhibited peaks at 542 and 560 nm in CHCl3, respectively, whereas the photoluminescence intensity of Polymer‐2 was very low in the solid state, presumably owing to the partial aggregation of the polymer molecules. © 2021 Society of Industrial Chemistry.

A Molecular Transformer: A π‐Conjugated Macrocycle as an Adaptable Host

AbstractHere, we report a facile method to synthesize a series of macrocycles with different conformations. The planar macrocycle dimer (1), twisted macrocycle trimer (2) and “figure‐eight” tetramer (3) are clearly elucidated by X‐ray single‐crystal analysis, in which the electron‐rich phenanthrene units offer the possibility of supramolecular assembly. As expected, in the solid state, 1 and 3 assemble into a columnar stack and an interlocking dimer, respectively, via π–π interactions between the phenanthrene units. Compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its enlarged ring size. 3 can deform from a figure‐eight into a boat‐shaped geometry to host a planar electron‐deficient guest using its electron‐rich phenanthrene units. When assembled with spherical electron‐deficient C60, interestingly, 3 further undergoes a conformational transformation from a figure‐eight to a belt shape in order to host C60. These supramolecular assembly behaviors of 3 demonstrate that it is an adaptable macrocyclic host for both planar molecules and fullerenes.

A Molecular Transformer: A π-Conjugated Macrocycle as an Adaptable Host.

Here, we report a facile method to synthesize a series of macrocycles with different conformations. The planar macrocycle dimer (1), twisted macrocycle trimer (2) and "figure-eight" tetramer (3) are clearly elucidated by X-ray single-crystal analysis, in which the electron-rich phenanthrene units offer the possibility of supramolecular assembly. As expected, in the solid state, 1 and 3 assemble into a columnar stack and an interlocking dimer, respectively, via π-π interactions between the phenanthrene units. Compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its enlarged ring size. 3 can deform from a figure-eight into a boat-shaped geometry to host a planar electron-deficient guest using its electron-rich phenanthrene units. When assembled with spherical electron-deficient C60 , interestingly, 3 further undergoes a conformational transformation from a figure-eight to a belt shape in order to host C60 . These supramolecular assembly behaviors of 3 demonstrate that it is an adaptable macrocyclic host for both planar molecules and fullerenes.

Polypyridyl-Based Copper Phenanthrene Complexes: Combining Stability with Enhanced DNA Recognition.

We report a series of copper(II) artificial metallo-nucleases (AMNs) and demonstrate their DNA damaging properties and in-vitro cytotoxicity against human-derived pancreatic cancer cells. The compounds combine a tris-chelating polypyridyl ligand, di-(2-pycolyl)amine (DPA), and a DNA intercalating phenanthrene unit. Their general formula is Cu-DPA-N,N' (where N,N'=1,10-phenanthroline (Phen), dipyridoquinoxaline (DPQ) or dipyridophenazine (DPPZ)). Characterisation was achieved by X-ray crystallography and continuous-wave EPR (cw-EPR), hyperfine sublevel correlation (HYSCORE) and Davies electron-nuclear double resonance (ENDOR) spectroscopies. The presence of the DPA ligand enhances solution stability and facilitates enhanced DNA recognition with apparent binding constants (Kapp ) rising from 105 to 107 m-1 with increasing extent of planar phenanthrene. Cu-DPA-DPPZ, the complex with greatest DNA binding and intercalation effects, recognises the minor groove of guanine-cytosine (G-C) rich sequences. Oxidative DNA damage also occurs in the minor groove and can be inhibited by superoxide and hydroxyl radical trapping agents. The complexes, particularly Cu-DPA-DPPZ, display promising anticancer activity against human pancreatic tumour cells with in-vitro results surpassing the clinical platinum(II) drug oxaliplatin.

Branched azomethines based on tris(2-aminoethyl)amine: Impact of imine core functionalization on thermal, electrochemical and luminescence properties

A series of imines based on tris(2-aminoethyl)amine was designed and synthesized to evaluate the effect of core functionalization with biphenyl, pyrene, anthracene, triphenylamine and phenanthrene units on selected properties. Their chemical structure was thoroughly characterized by NMR and FTIR spectroscopy and elemental analysis. All compounds were crystalline (except for imine with triphenylamine units) and melted in the wide temperature range of 99–187 °C, according to the structure of the substituent. DSC measurements revealed that the studied compounds can be converted into amorphous material with glass transition occurring for temperatures between 16 and 55 °C. The imines were electrochemically active and underwent oxidation and reduction processes as found using CV and DPV methods. Density functional theory was employed for optimizing the imines geometry, as well as for calculating HOMO and LUMO orbital energies together with ionization potentials and electron affinities. The absorption and photoluminescence in the UV–Vis spectral range, both in solution and in the solid state as films on glass substrates were studied. When dissolved in chloroform, they emitted light with quantum yields ranging from 0.54 to 22%. In the solid state they exhibited emission in the range of 380–515 nm. The selected compounds were preliminarily tested as components in light emitting diodes. The ability neat azomethines for electroluminescence in diode ITO/PEDOT:PSS/imine/Al was demonstrated.

Structural features of liquefaction residue from Shenmu-Fugu subbituminous coal

Liquefaction residue (LRSFSBC) from Shenmu-Fugu subbituminous coal was ultrasonically extracted with petroleum ether, methanol, cyclohexane, ethyl acetate, acetone, carbon disulfide (CDS) and isometric CDS/acetone mixture (IMCDSAM), respectively. A number of alkanes, arenes, arenols, alkanols, alkenones, esters, and nitrogen-containing organic compounds were identified according to the analyses with Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer, direct analysis in real-time ionization source coupled with ion trap mass spectrometer, and solid-state 13C nuclear magnetic resonance (SS 13C NMR). The tetra- and penta-substituted anthracene or phenanthrene unit could be the average structures in LRSFSBC by SS 13C NMR analysis. The main intermolecular interactions among the organic species in LRSFSBC are π–hydrogen bonds and π–π interactions. These interactions are also the cause for “capsule” formation. Stronger interactions between LRSFSBC and solvents, especially CDS and IMCDSAM, destroyed the interactions and thereby led to high extract yields.

Supramolecular Assembly of DNA-Phenanthrene Conjugates into Vesicles with Light-Harvesting Properties.

Vesicle-shaped supramolecular polymers are formed by self-assembly of a DNA duplex containing phenanthrene overhangs at both ends. In the presence of spermine, the phenanthrene overhangs act as sticky ends linking the DNA duplexes together. In aqueous solution, the assembly leads to vesicles with a diameter in the range of 50-200 nm. Fluorescence measurements show that the assembled phenanthrene units act as light-harvesting complexes and transfer absorbed energy to an acceptor, such as pyrene or Cy3, which can either be directly added to the polymer or attached via a complementary DNA strand. The presence of DNA in the nanostructures allows the construction of light-harvesting vesicles that are amenable to derivatization with different functional groups.

Double trap: A single product from the THF-initiated interception of a cyclopropylidene(oid) and its rearranged strained cyclic allene

The reaction of 1,1-dibromo-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene (3) with butyllithium in THF at ∼ −70 °C, followed by quenching with water at room temperature, led to a complex mixture of products which included a trace amount of the unusual pyran derivative, 3-(5H-dibenzo[a,c][7]annulen-5-yl)-2-(phenanthren-9-yl)tetrahydro-2H-pyran (6). The X-ray crystal structure of 6 revealed a phenanthrene unit α to the oxygen and a dibenzocycloheptene moiety in the β position. The formation of 6 is mechanistically rationalized on the basis of the initially generated cyclopropylidenes(oid) (4/5) interacting with THF to form an oxonium ylid 7 which then undergoes a ring expansion to produce the pyran framework in 10. Subsequent reaction of 10 with the strained dibenzocycloheptatetraene 2, resulting from ring opening of 4/5, leads to the observed product 6. To the best of our knowledge, this work documents the first example of a cyclopropylidene(oid) and its ring-opened allene trapped into a single product.

A cyclopenta[hi]acephenanthrylene bearing two benzoannelated [3.3.3]propellane units: extension of triptindane chemistry

The McMurry reaction of triptindan-9-one (2), a three-fold benzoannelated Cs-symmetrical [3.3.3]propellane ketone, gave trans-9,9′-bitriptindanylidene (5), a sterically crowded stilbene hydrocarbon bearing two E-oriented triptindane moieties, in good yield. Photoisomerization of 5 generated the corresponding cis-stilbene 8 in a photostationary E:Z mixture (55:45), which adopts a similarly crowded C2-symmetrical conformation that is apparently static on the NMR timescale. Photocyclodehydrogenation of 5 via 8 in benzene solution afforded the title hydrocarbon 6, a 1,2,9,10-tetrahydrocyclopenta[hi]acephenanthrylene merged with two triptindane units, in 85% yield. X-ray structure analysis of 6 revealed an essentially planar phenanthrene unit but significant steric repulsion between the pairs of opposite methylene groups of the [3.3.3]propellane cores, giving rise to a C2-symmetrical conformation. Reaction of 2 under modified McMurry conditions (DME instead of THF as a solvent) gave the saturated dimer, 9,9′-bitriptindanyl 7, as a mixture of diastereomers. Attempts to synthesize “columnene” (4), an elusive barrelene derivative fused with two triptindane caps, by three-fold McMurry reaction of triptindane-9,10,11-trione (3) failed.

Crystal structure of 4,5-di-bromo-phenanthrene.

The synthesis and crystal structure of the title compound, C14H8Br2, is described. The mol-ecule is positioned on a twofold rotation axis and the asymmetric unit consists of half a mol-ecule with the other half being generated by symmetry. The presence of two large bromine atoms in the bay region significantly distorts the mol-ecule from planarity and the mean planes of the two terminal rings of the phenanthrene system are twisted away from each other by 28.51 (14)°. The torsion angle between the two C-Br bonds is 74.70 (14)° and the distance between the two Br atoms is 3.2777 (13) Å. The mol-ecules pack in layers in the crystal, with the centroids of the central rings of the phenanthrene units in adjacent layers separated by a distance of 4.0287 (10) Å. These centroids are shifted by 2.266 (6) Å relative to each other, indicating slippage in the stacking arrangement. Furthermore, the distance between the centroids of the terminal and central rings of the phenanthrene units in adjacent layers is slightly shorter at 3.7533 (19) Å. While all of the mol-ecules within each layer are oriented in the same direction, those in adjacent layers are oriented in the opposite direction, leading to anti-parallel stacks.