New Azulene-Type Sesquiterpenoids from the Fruiting Bodies of Lactarius deliciosus

In the^(1)H NMR-guided fractionation of extracts from the edible mushroom Lactarius deliciosus,two new azulene-type sesquiterpenoids,7-isopropenyl-4-methyl-azulene-1-carboxylic acid(1)and 15-hydroxy-3,6-dihydrolactarazulene(2),together with seven known compounds were characterized.Their structures were determined on basis of spectroscopic evidence,as well as by comparing with literature data.Amongst the known metabolites,the^(13)C NMR assignment of 15-hydroxy-6,7-dihydrolactarazulene(3)is reported here for the first time.Moreover,7-acetyl-4-methylazulene-1-carbaldehyde(5)displayed a moderate antibacterial activity against Staphylococcus aureus.

Theoretical studies on the one-and two-photon absorption properties of azulenylporphyrins and azulene-fused porphyrins

The electronic structures, one-photon absorption （OPA） and two-photon absorption （TPA） properties of the azulenylporphyrins and azulene-fused porphyrins have been comparatively studied by using DFT/B3LYP/6-31G（d） and the ZINDO/SDCI method. With the number of azulenyl groups increasing, the OPA wavelengths of all molecules are red-shifted in 400-600 nm and the two-photon absorption cross section is gradually enlarged. The azulene-fused structures facilitate an expanding conjugated area and increasing TPA cross section. The origin of TPA properties of studied compounds is studied with a two-level model. In summary, the azulene-fused porphyrins exhibit strong two-photon absorption.

Optimized One-Step Preparation of a Bioactive Natural Product,Guaiazulene-2,9-dione

We previously isolated a natural product, namely guaiazulene-2,9-dione showing strong antibacterial activity against Vibrio anguillarum, from a gorgonian Muriceides collaris collected in South China Sea. In this experiment, guaiazulene-2,9-dione was quantitatively synthesized with an optimized one-step bromine oxidation method using guaiazulene as the raw material. The key reaction condition including reaction time and temperature, drop rate of bromine, concentration of aqueous THF solution, respective molar ratio of guaiazulene to bromine and acetic acid, and concentration of guaiazulene in aqueous THF solution, were investigated individually at five levels each for optimization. Combined with the verification test to show the absolute yield of each optimization step, the final optimal condition was determined as: when a solution of 0.025 mmol m L-1 guaiazulene in 80% aqueous THF was treated with four volumes of bromine at a drop rate of 0.1 m L min-1 and four volumes of acetic acid at-5℃ for three hours, the yield of guaiazulene-2,9-dione was 23.72%. This was the first report concerning optimized one-step synthesis to provide a convenient method for the large preparation of guaiazulene-2,9-dione.

Nonalternant isomer of pentacene fusing two azulene units

Azulene is a promising building block for creating innovative polycyclic aromatic hydrocarbons. This study involved the construction of three nonalternant isomers of pentacene by fusing two azulene units, named Az-PH1/2/3. Az-PH1 was initially developed through the rhodium(Ⅱ)-catalyzed cyclization of bis(N-tosylhydrazone)s. Intriguingly, Az-PH1 was also unexpectedly obtained during a nickel(0)-catalyzed one-step tandem reaction. We investigated the optical and electrochemical properties, aromaticity, and photo-oxidative stability of Az-PH1, comparing it with the well-known pentacene using density functional theory, electrochemical, and photophysical tests. Our results showed that the azulene-fusing strategy resulted in a molecule with narrow optical bandgaps(2.046 eV) and a long half-life time under ambient air conditions.

Azulene-based organic functional molecules for optoelectronics

Design and synthesis of new organic functional materials with improved performance or novel properties are of great importance in the field of optoelectronics.Azulene,as a non-alternant aromatic hydrocarbon,has attracted rising attention in the last few years.Different from most common aromatic hydrocarbons,azulene has unique characteristics,including large dipole moment,small gap between the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO）.However,the design and synthesis of azulene-based functional materials are still facing several challenges.This review focuses on the recent development of organic functional materials employing azulene unit.The synthesis of various functionalized azulene derivatives is summarized and their applications in optoelectronics are discussed,with particular attention to the fields including nonlinear optics（NLO）,organic field-effect transistors（OFETs）,solar cells,and molecular devices.

The unusual physicochemical properties of azulene and azulene-based compounds

Azulene,an isomer of naphthalene,has become one of hot chemical structures in the research field of functional materials,due to its anti-Kasha's rule emissions and unusual physicochemical properties(e.g.,photophysical,electrochemical,and photoelectrochemical properties).In the past,the synthesis of azulene-based compounds is relatively inconvenient.Recently,there have been more and more reports about the synthesis strategies of the azulene-based compounds for finely tuning the physicochemical properties.In this article,we introduce several synthetic methods for kinds of azulene-based compounds which has unusual physicochemical properties.With these convenient methods and unique physicochemical properties,azulene-based compounds can be applied into many fields such as specific bioimaging,advanced molecular switches,organic field-effect transistor(OFET),organic light emitting diode(OLED),solar cells,and so forth.And these properties are also summarized here.

Theoretical Study of Remote Substituent Effects on X-H （X=CH2, NH, O） Bond Dissociation Energies of Azulene

In the study, the X-H （X=CH2, NH, O） bond dissociation energies （BDE） of para-substituted azulene （Y-C10H8X-H） were predicted theoretically for the first time using Density Functronal Theory （DFT） methods at UB3LYP/6-311 ＋ ＋g（2df,2p）//UB3LYP/6-31 ＋g（d） level. It was found that the substituents exerted similar effects on the X-H BDE of azulene as those on benzene, except for 6-substituted 2-methylazulene. Owing to the substituent-dipole interaction, the reaction constants （ρ^＋） of 2- and 6-Y-CIoHsX-H （X=NH and O only） varied violently. The origin of the substituent effects on the X-H BDE of azulene was found, by both GE/RE and SIE theory, to be directly associated with variation of the radical effects, although the ground effects also played a modest role in determining the net. substituent effects.

Modulation of the Second Order Nonlinear Optical Properties of Helical Graphene Nanoribbons Through Introducing Azulene Defects or/and BN Units

The current study has obtained excellent potential nonlinear optical(NLO)materials by combining density functional theory methods with sum-over-states model to predict the second order NLO properties of helical graphene nanoribbons(HGNs)through introducing azulene defects or/and BN units.The introduction of these functional groups deforms the pristine HGN(compression or tension)and enhances obviously the static first hyperpolarizability(〈β0〉)of system by up to two orders of magnitude.The tensor components along the helical axis of HGNs play a dominant role in the total〈β0〉.The azulene defects and the BN units polarize the pristine HGN to different degrees,and the azulenes and contiguous benzenes are involved in the major electron excitations with significant contributions to〈β0〉but the BN units are not.The BN-doped chiral HGNs have good kinetic stability and strong second order NLO properties(6.84×10^(5)×10^(−30) esu),and can be a potential candidate of high-performance second order NLO materials.The predicted two-dimensional second order NLO spectra provide useful information for further exploration of those helicenes for electro-optic applications.

A simple,azulene-based colorimetric probe for the detection of nitrite in water

We describe the synthesis and evaluation of an azulene-based chemodosimeter for nitrite.The probe was found to undergo two distinct color changes upon introduction of aqueous nitrite ion.A near-instant formation of a grey color provides a qualitative indication of the presence of nitrite,followed by the formation of a deep-yellow/orange color,the endpoint from which quantitative data can be derived.The azulene probe exhibits 1:1 stoichiometry of reaction with nitrite in water,and is selective for nitrite over other anions.The azulene probe was applied to determine nitrite content in cured meat,and compared with the British Standard testing procedure(Griess test).The value obtained from the azulene-based probe agreed closely with the standard test.Our procedure only requires the preparation of one standard solution,instead of the three required for the standard Griess test.

An efficient one-pot synthesis of thiophene-fused pyrido[3,2-a]azulenes via Gewald reaction

A simple and efficient procedure was developed for the synthesis of 11H（2H）-4-oxothiophene[3＇,4＇：6,5]pyrido[3,2-a]azulene-10-carboxylates（3） in moderate to good yields via the Gewald reaction of ethyl 1-cyanoacetyl-2-methoxyazulene-3-carboxylate（1） with carbonyl compounds（2） and elemental sulfur utilizing imidazole as catalyst.This reaction provides a new procedure for synthesis of pyridinone-fused azulenes.

Anti-inflammatory and Chemical Composition of Two Plants Family Asteraceae Growing in Saudi Arabia

The study was designed to investigate the anti-inflammatory and composition of essential oil of two plant family Asteraceae, Achillea fragrantissima and Lactuca serriola growing under dry desert condition. The anti-inflammatory effect of volatile oil extracted by hydrodistillation of plants was studied using carrageenan induced paw edema. Essential oil （100 mg/kg） and （200 mg/kg） were tested the two plant show high inhibition after 4 h, concentration （200 mg/kg） show high inhibition than （100 mg/kg） after 4 h. Sesqui sabinene hydrate, Azuline and u-Bisabolol are the main constituents of the volatile oil were investigated by capillary GC （gas chromatography） and GC-MS （gas chromatography-mass spectrometry）. The discussion shows the role of chemical compound azulene in inflammatory inhibition.

Large negative hyperpolariza-bilities (β) of the protonated Schiff bases of the azulenic retinal analogues

The molecular first hyperpolarizabilities (β) and electronic properties of some azulenic retinal analogues and their derivatives have been investigated theoretically by employing semiempirical approaches. The results indicate that the protonated Schiff bases (PSB) of the 2-substituted azulenic retinal analogues possess extremely large negative β values and very good transparency. These can be attributed to the large difference between the ground state dipole moment and the first excited state dipole moment according to the electronic property analysis. The characteristic blue-shifted absorption in polar solvents of the 2-substituted PSB chromophores can be well explained by the negative solva-tochromic effects. The largest calculated |μβ| value can reach the magnitude of 10-44 esu, which is close to the highest reported values of synthesized chromophores.

Second-order Nonlinear Optical Properties of a Series of Az-ulene Derivatives

The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperpolariza-bilities of chromophores holds the same tendency as the experimental results. In addition, the static first hyperpo-larizability 0 of molecules was calculated by means of the Sum-Over-States (SOS) expression and the two-level formula respectively. The results show that these molecules possess large static first hyperpolarizabilities and the 0 value increases as the donor or acceptor strength enhances; the distorted degree of molecules has also an important influence on the 0 value.

BN Fused Diazulenyl-Carbazole:Synthesis,Structure,and Properties

Main observation and conclusion By combination of two special structural units,a boron-nitrogen-fused polycyclic aromatic hydrocarbon and azulene with strong intramolecular dipoles,a novel BN aromatics,BN-Az,has been designed and synthesized with unique characteristics.The structure,optical and electrochemical properties,as well as charge transport property of BN-Az have been investigated.Notably,BN-Az selectively responds to fluoride ions and protons with a significant color change,which could also be monitored by NMR spectra and single-crystal X-ray analysis,indicating its potential as an effective ion sensing material in stimuli-responsive electronic devices.

Azulenoisoindigo: A building block for π-functional materials with reversible redox behavior and proton responsiveness

Azulene, one of representative nonbenzenoid aromatic hydrocarbons, exhibits unique molecular structure and distinctive physical and chemical properties. Herein, azulenoisoindigo(Az II), an azulene-based isoindigo analogue, is designed and synthesized, which has a twisted molecular backbone and R/Sisomers in single crystals. Interestingly, Az II shows the characteristics of both isoindigo and azulene,such as reversible redox behavior and reversible proton responsiveness. UV-vis-NIR,^(1)H NMR and electron paramagnetic resonance(EPR) measurements were carried out to get insights into the possible mechanism of the proton-responsive property of Az II. The results demonstrated that only one azulenyl moiety of molecule of Az II was protonated and deprotonated, and the protonated Az II can be further oxidized to form azulenium cation radicals.