Polycyclic Aromatic Aldehydes Research Articles

Solvent- and Concentration-Induced Topological Transformation of a Ruthenium(II)-Based Trigonal Prism to a Triply Interlocked [2] Catenane.

Synthesis of interlocked supramolecular cages has been a growing field of interest due to their structural diversity. Herein, we report the template-free synthesis of a Ru(II) triply interlocked [2] catenane using coordination-driven self-assembly. The self-assembly of a triazine-based tripyridyl donor L (2,4,6-tris(5-(pyridin-4-yl)thiophen-3-yl)-1,3,5-triazine) with a dinuclear Ru(II) acceptor M (Ru2(dhnq)(η6-p-cymene)2)(CF3SO3)2) yielded two distinct structures depending on the solvent and concentration. In methanol, a triply interlocked metalla [2] catenane (MC2) was formed, whereas in nitromethane, a non-interlocked cage (MC1) was obtained. The non-interlocked cage MC1 was gradually converted to MC2 in nitromethane by the increase in the concentration of cage MC1 from 0.5 to 9 mM. The interlocked cage (MC2) was stable after formation and was unaffected by the change in concentration. Notably, the free cage (MC1) exhibited host-guest interactions with polycyclic aromatic aldehydes, stabilizing the non-interlocked structure even at higher concentrations. In contrast, the triply interlocked [2] catenane (MC2) remains stable due to self-penetration and does not encapsulate guest molecules. This work showcases the stimuli-induced irreversible structural transformation of a triangular prismatic cage to its triply interlocked [2] catenane by employing metal-ligand coordination chemistry.

Knoevenagel reaction promoted by functional ionic liquids with primary and tertiary amines

ABSTRACT Functional ionic liquids have been widely used in the fields of synthetic chemistry, analytical chemistry, electrochemistry and material chemistry owing to their excellent properties such as easy structure modification and adjustable properties. In this work, a series of basic functionalized ionic liquids were prepared from 1, 4-diazabicyclo [2.2.2] octane (DABCO) or hexamethylenetetramine (HMTA) with various halogenated hydrocarbons, then these functional ionic liquids and water were used as solvent-catalyst system in the Knoevenagel reaction of various aldehydes with ethyl cyanoacetate or malononitrile, the influence of the structure of the ionic liquid and the content of water was investigated. The results showed that the composite solvent-catalyst system mixed by the functional ionic liquid N-(3-aminopropyl)-1,4-diazabicyclo [2.2.2] octane bromide with water can effectively promote the Knoevenagel reaction and the alkalinity of amine and hydrogen bond play an important role. Aromatic aldehydes with electron-donating or electron-withdrawing groups can obtain the target product at an excellent yield (79-99%). It is worth noting that the polycyclic aromatic aldehydes with high steric hindrance, 86%-95% yields of the object products were also obtained after 15 h-25 h. Furthermore, the catalyst could be reused for 6 times without any loss in its catalytic activity. The composite solvent-catalyst system mixed by the Functional ionic liquid N-(3-aminopropyl)-1,4-diazabicyclo[2.2.2]octane bromide with water can effectively promote the Knoevenagel reaction, even for the electron-rich aromatic aldehydes with poor reactivity, high yields of the target products and fast reaction rate were also obtained at room temperature.

Excimer emission from polycyclic arenes bearing triphenylmethyl group: Solid-state fluorescence, mechanofluorochromism, aggregation-induced emission and cell imaging application

The excimer emission based on discrete π-stacked dimers of polycyclic π-systems has generated significant interest in the structure-luminescence relationship of excimers owing to their ultra-large Stokes shift. Herein, a series of excimer emissive luminogens were obtained by conjugating different polycyclic aromatic aldehydes (anthraldehyde, pyrenealdehyde and perylenealdehyde) with triphenylmethylamine. In crystalline states, all the molecules were arranged in the form of π-stacked arene dimers which were spatially isolated from each other by the bulky triphenylmethyl groups, and thus emitted bright excimer emission. The anthracene and pyrene derivatives showed fluorescence enhancement responses to grinding and the enhanced fluorescence could recover to the original state upon heating. The aggregation-induced emission (AIE) properties of them were dependent on the shapes and sizes of the polycyclic aromatic groups. The pyrene derivative showed the most excellent excimer-based AIE behavior among them. All of them were more apt to exhibit the excimer emission when formed nanoparticles with pluronic F-127 than that without pluronic F-127. Furthermore, PETP was utilized for bioimaging of living Hela cells and the high-resolution image was observed.

Sulfur-promoted, one-pot, and metal-free conversion of aromatic aldehydes to nitriles using an inorganic ammonium salt as the nitrogen source

A simple protocol for the sulfur-promoted conversion of aromatic aldehydes to aromatic nitriles has been developed. This strategy enables the one-pot conversion of inexpensive and readily available aromatic aldehydes into highly valuable aromatic nitriles using a cheap inorganic ammonium salt as the nitrogen source in the absence of metals. Significantly, a broad scope of substrates was explored using this strategy, and various groups, including alkyl, alkoxyl, alkylthiol, hydroxyl, amino, aryl, alkenyl, cyano, carboxyl, and borate ester groups were tolerated, and good to excellent yields were achieved in most cases. Additionally, polycyclic aromatic aldehydes and heteroaromatic aldehydes also could be converted to the corre-sponding nitriles with satisfactory yields. This method can be utilized as a powerful tool for the cyanation of complex molecules.

Pepsin-Catalyzed Asymmetric Cross Aldol Reaction Promoted by Ionic Liquids and Deep Eutectic Solvents

Pepsin was found to catalyze asymmetric cross aldol reactions of aromatic and polycyclicaromatic aldehydes with cyclic ketones in ionic liquids and deep eutectic solvents for the first time. Pepsin exhibited high catalytic activity and excellent stereoselectivity in ionic liquids and deep eutectic solvents in the presence of moderate water. High yields of up to 93.1%, excellent enantioselectivities of up to 96% ee, and good diastereoselectivities of up to 5:95 dr were achieved.

Cyclic Bis-porphyrin-Based Flexible Molecular Containers: Controlling Guest Arrangements and Supramolecular Catalysis by Tuning Cavity Size.

Three cyclic zinc(II) bis-porphyrins (CB) with highly flexible linkers are employed as artificial molecular containers that efficiently encapsulate/coordinate various aromatic aldehydes within their cavities. Interestingly, the arrangements of guests and their reactivity inside the molecular clefts are significantly influenced by the cavity size of the cyclic containers. In the presence of polycyclic aromatic aldehydes, such as 3-formylperylene, as a guest, the cyclic bis-porphyrin host with a smaller cavity (CB1) forms a 1:1 sandwich complex. Upon slightly increasing the spacer length and thereby the cavity size, the cyclic host (CB2) encapsulates two molecules of 3-formylperylene that are also stacked together due to strong π-π interactions between them and CH-π interactions with the porphyrin rings. However, in the cyclic host (CB3) with an even larger cavity, two metal centers of the bis-porphyrin axially coordinate two molecules of 3-formylperylene within its cavity. Different arrangements of guest inside the cyclic bis-porphyrin hosts are investigated by using UV/Vis, ESI-MS, and 1 H NMR spectroscopy, along with X-ray structure determination of the host-guest complexes. Moreover, strong binding of guests within the cyclic bis-porphyrin hosts support the robust nature of the host-guest assemblies in solution. Such preferential binding of the bis-porphyrinic cavity towards aromatic aldehydes through encapsulation/coordination has been employed successfully to catalyze the Knoevenagel condensation of a series of polycyclic aldehydes with active methylene compounds (such as Meldrum's acid and 1, 3-dimethylbarbituric acid) under ambient conditions. Interestingly, the yields of the condensed products significantly increase upon increasing spacer lengths of the cyclic bis-porphyrins because more substrates can then be encapsulated within the cavity. Such controllable cavity size of the cyclic containers has profound implications for constructing highly functional and modular enzyme mimics.

Complexes of cis-bis(triphenylphosphine)ruthenium(II) with N,S-donor thiobenzhydrazones of polycyclic aromatic aldehydes: Synthesis, properties and structures

Reactions of [Ru(PPh3)3Cl2], H2Ln (polycyclic aromatic aldehyde thiobenzhydrazones ArCHNNHC(S)Ph, n=1–4 for Ar=1-naphthalenyl, 9-anthracenyl, 9-phenanthryl and 1-pyrenyl, respectively) and NaOAc in 1:2:2mol ratio in methanol produces ruthenium(II) complexes of formula cis-[Ru(PPh3)2(HLn)2] (1–4) in ∼80% yields. Microanalysis (CHN), magnetic susceptibility, solution conductivity, spectroscopic (IR, UV–Vis, NMR and fluorescence) and cyclic voltammetric measurements have been used for the characterization of 1–4. The complexes are non-electrolytic and diamagnetic. In the electronic spectra, the complexes display multiple absorptions within 505–245nm due to metal-to-ligand charge transfer and ligand centred transitions. The emission spectral features of 1–4 indicate ligand centred emissive states. Molecular structures of 3 and 4 have been determined by X-ray crystallography. In each of 3 and 4, two thioamidate-N,S coordinating (HLn)− and two mutually cis oriented PPh3 molecules assemble a distorted octahedral N2S2P2 coordination sphere around the metal centre. Cyclic voltammograms of 1–4 show an oxidation response within E1/2=0.76–0.86V (ΔEp=90–100mV) versus Ag/AgCl.

Highly selective oximation of aldehydes by reusable heterogeneous sandwich-type polyoxometalate catalyst

The selectivity of oximation of a variety of aliphatic aldehydes and polycyclic aromatic aldehydes as substrates has been greatly improved by applying a reusable heterogeneous sandwich-type polyoxometalate as catalyst under mild conditions.

ChemInform Abstract: Polycyclic peri‐Hydroxycarbonyl Compounds and Their Derivatives

AbstractReview: 305 refs.

Cobalt(II)-catalyzed reaction between polycyclic aromatic aldehydes and acetic anhydride. Formation of acylals, not 1,2-diketones

Several polycyclic aromatic aldehydes were found to react with acetic anhydride in acetonitrile in the presence of excess CoCl 2 to afford the corresponding acylals [ArCH(OAc) 2 ]. The results are not consistent with the literature report (Ahmad, S.; Iqbal, J. J. Chem. Soc., Chem. Commun. 1987, 692) that substituted benzaldehydes afford 1,2-diketones under similar conditions. The cobalt(II)chloride probably promotes acylal formation through its weakly Lewis acid character

ChemInform Abstract: The Baeyer‐Villiger Reaction of Polycyclic Aromatic Aldehydes: Preparation of Polycyclic Phenols.

Baeyer–Villiger reactions of such polycyclic aromatic aldehydes as 2-dibenzofurancarbaldehyde with various peroxy compounds have been studied in detail, giving predominantly the corresponding phenols.

The Baeyer–Villiger Reaction of Polycyclic Aromatic Aldehydes: Preparation of Polycyclic Phenols

Abstract Baeyer–Villiger reactions of such polycyclic aromatic aldehydes as 2-dibenzofurancarbaldehyde with various peroxy compounds have been studied in detail, giving predominantly the corresponding phenols.

Correlations Between Carbonyl Vibrational Properties of Polycyclic Aromatic Aldehydes and Electronic Properties of the Corresponding Hydrocarbons

Good correlations exist between both the carbonyl stretching frequency and the carbonyl bond order of the monoaldehydes of polycyclic aromatic hydrocarbons and the HMO atom localisation energies or PMO reactivity numbers of the corresponding hydrocarbons at the carbon centres contiguous to the CHO group. Applications of these correlations are discussed

Spectroscopie Ultraviolette D'Une Série D'Aldéhydes Dérivés D'Hydrocarbures Polycycliques Aromatiques: I. Étude Théorique de la Fréquence de la Transition 1La et de la Position Des Bandes De Transfert de Charge Avec le Tétracyanoéthylène

AbstractThe frequencies of the 1La transitions of polycyclic aromatic aldehydes are related linearly to the energy gap between the highest bonding and the lowest anti‐bonding orbitals in these molecules calculated by an iterative Hückel‐L. C. A. O.‐method. Solutions of the same derivatives and tetracyanoethylene in chloroform show a new absorption band which may be attributed to a charge‐transfer complex. A linear relation is found between the energies of these bands and the highest occupied molecular orbital of the aldehydes.

The condensation of rhodanine and derivatives with polycyclic aromatic aldehydes

AbstractThe condensation products of rhodanine, 3‐ethylrhodanine and 3‐phenyl‐rhodanine with various polycyclic aromatic aldehydes have been prepared with a view to obtaining compounds with increased bacterial and fungicidal properties. The aldehydes were chosen to yield products of similar skeletal configuration to the less accessible alkyl substituted compounds. It is known that substituted benzylidene‐rhodanine derivatives show increased bacterial activity and the products obtained, by virtue of their structure, should show activity similar to di‐ and tetra‐alkyl substituted derivatives. Condensations were carried out in both ammoniacal and acid media and crystalline coloured condensation products were obtained in good yield.