Pyrazine Research Articles

Copper(II) complexes of hindered diazines: tetramethylpyrazine

Two copper(II) complexes of 2,3,5,6-tetramethylpyrazine (tmpz) are reported, [Cu(tmpz)Cl2]n (1), and [Cu(tmpz)Br2]n (2). The compounds crystallize in the monoclinic space group C2/m as pyrazine-bridged linear chains (parallel to the b-axis). The pyrazine rings are oriented nearly perpendicular to the CuN2X2 coordination planes. Adjacent chains parallel to the a-axis are offset by ½ unit cell translation parallel to the b-axis rendering the closest interchain X…X contact distance to be 4.83(2) Å (1) or 4.59(1) Å (2). Parallel to the c-axis, the chains are further separated by the methyl groups. Magnetic interactions for 2 are well fit by the uniform Heisenberg chain model with a Curie-Weiss correction for interchain interactions giving: J/kB = −19.2(1) K, Curie constant (CC) = 0.451(1) emu-K/mol-Oe and θ = −0.18(1) K.

Iridium(III) and Rhodium(III) Complexes With Imidazo[1,5‐a]pyridine‐Based Cyclometalating Ligands: Synthesis, Photophysical and Electrochemical Properties, and Catalytic Activities Toward the [4 + 2] Cycloaddition Reactions of Tertiary Anilines and Maleimides

ABSTRACTEighteen cationic iridium(III) (PC1–PC9) and rhodium(III) (PC10–PC18) complexes with a general formula [M(ppy)2(N^N)]+ (ppy = 2‐phenylpyridine; N^N = imidazo[1,5‐a]pyridine‐based ancillary ligands bearing different halogen atoms) were synthesized and characterized. The photophysical and electrochemical properties and catalytic activities of these complexes were investigated, and their properties were supported by density functional theory (DFT) calculations. The aims of this work were to study the influences of changes in the metal centers, the replacement of the pyridine ring by the pyrazine ring, the extension of the conjugation systems, and the attachment of different halogen atoms at the backbone of imidazo[1,5‐a]pyridine on the photophysical, electrochemical, and catalytic properties of PC1–PC18. It is found that the variation in the metal centers affected these properties the most. The experimental and calculated results revealed that the photophysical and electrochemical behaviors of iridium(III) complexes and rhodium(III) compounds are different. Upon photoexcitation, the iridium(III) complexes exhibited intense and long‐lived (6.96–13.03 μs) green to orange–red luminescence in acetonitrile at 298 K, and the emissions originated from 3ILCT transitions. The rhodium(III) complexes showed blue to green emissions with shorter excited‐state lifetimes (2.87–4.94 μs) than those of the iridium(III) complexes in acetonitrile. The emissions of the rhodium(III) complexes were attributed to 3MLCT or mixed 3MLCT/3ILCT/3LLCT transitions. All the complexes are catalytically active for the [4 + 2] cycloaddition reactions of tertiary anilines with maleimides, producing a series of tetrahydroquinoline derivatives.

Uncommon Phosphonylation of Pyrazine‐2,3‐dicarbonitrile Derivatives via C(sp2)−CN Bond Cleavage

AbstractA direct phosphonylation of the C(sp2)−CN bond under mild catalytic and non‐catalytic reaction conditions is disclosed. Pyrazine‐2,3‐dicarbonitriles are readily coupled with HPO(OEt)2 to produce the corresponding dialkoxyphosphoryl‐substituted pyrazines. The phosphonylation reaction occurs in the presence of a base (Et3N, Cs2CO3) as nucleophilic substitution of the CN groups. The yield of target diphosphonates depends on the nature of substituents in the 5,6‐positions of the pyrazine ring: it exceeds 90 % for di‐5,6‐aryl‐substituted pyrazines and is significantly lower when electron‐donating alkyl (n‐propyl) groups are attached to the 5,6‐positions. It should be noted that for pyrazine‐2,3‐dicarbonitriles bearing vicinal 4‐bromophenyl groups, the nucleophilic phosphonylation leading to C−CN/P−H coupling in the pyrazine ring is predominant over Pd‐catalyzed Hirao's C−Br/P−H coupling reaction in phenyl rings. Detailed structural characterization, both in solution by means of 1H, 13C and 31P NMR spectroscopy and in the solid state by single crystal X‐ray diffraction, of a series of newly synthesized pyrazine phosphonates is reported.

Manipulating Intramolecular Charge Transfer in Terpyridine Derivatives Towards "Turn-On" Fluorescence Chemosensors for Zn2.

A series of donor-acceptor (D-A) terpyridine derivatives with various intramolecular charge transfer interactions have been successfully synthesized bearing phenyl, methoxyphenyl, N-butyldiphenylamine (DPA), and triphenylamine (TPA) as electron-donors and terpyridine (TPY), 2,6-di(pyrazin-2-yl)pyridine (PYDPZ), and N,N-dimethylated PYDPZ (PYDPZ-2CH3) as electron acceptors. Upon the introduction of pyrazine rings instead of pyridine ones and further selective N,N'-dimethylation, the intramolecular D-A interactions are significantly enhanced, resulting in the remarkable reduced intramolecular charge transfer (ICT) transitions and quenched PL emissions in CH2Cl2 solution. However, their ICT emissions are clearly recovered upon adding Zn2+. Especially, for double positively charged compound 12, the Zn2+-induced "turn-on" green emission (λmax, em=518 nm, Φ=0.24) with excellent sensitivity (I/I0=77) and selectivity (IZn/ICd=23) is detected. Under the optimized experimental condition (EtOH-H2O (9 : 1, v/v), containing 0.05 M HEPES buffer (pH=7.4)), this probe is used to quantitative determination of Zn2+ in a water sample with an average recovery of 97.5 %. Furthermore, the probe is applied to imaging of Zn2+ ions in HeLa cells and its mechanism is confirmed by the molecular dynamics simulation, in which lower coulomb potential for membrane surface adsorption and energy barrier for membrane translocation can be found.

Pyrazine-Based Iodine-Containing Biocidal Materials: Enhanced Energy Performance and Reduced Corrosion Risk.

Biosafety is crucial to the common interests of all humanity. Currently, global biosafety governance is a challenge and poses significant opportunities. With the escalating challenges posed by microorganisms, there is an urgent need to develop advanced biocidal materials. In this work, we introduce a class of iodine-containing high-energy biocidal materials, utilizing pyrazine rings with good thermal stability as nitrogen-rich high-energy backbones, to address the issues of corrosion and hygroscopicity associated with N-H acidic protons in traditional iodine-containing azole compounds. Employing nucleophilic substitution and coupling reactions, we successfully synthesized two distinct series of eight compounds (Series A: BQDI, BQFI, BQDIO; Series B: BBQ3I, BBQ4I, BBQNI, MBQ5I, and MBQDI), which exhibit a high iodine content and enhanced detonation pressure. Notably, compounds BQDIO and BBQNI show detonation pressures of 13.70 and 16.52 GPa, respectively, both exceeding the 10 GPa of traditional iodine-containing biocidal materials. This improvement is crucial for expanding the diffusion range of biocidal substances and enhancing the biocidal efficiency of these materials. Pyrazine-based iodine-containing compounds have revolutionized the performance of biocidal materials, addressing corrosion issues and paving the way for the development of efficient, stable, and safe biocidal materials.

Construction of homogeneous electron collection center at buried interface based on triazine-based graphdiyne for efficient perovskite solar cells

The properties of the buried interface between electron transport layer (ETL) and perovskite is critical factors to influence the performance of conventional perovskite solar cells (PSCs). Herein, functionalized triazine-based graphdiyne (Tz-GDY) nanospheres are prepared and employed to build up electron collection center and optimize the SnO2/perovskite interface. The pyrazine ring with homogeneous N element distribution and alkyne bond of Tz-GDY can passivate the undercoordinated Sn to remodel the electron density distribution around the Sn atoms and thus effectively eliminate the trap defects and inhibit the recombination loss significantly. In addition, the as-prepared Tz-GDY based nanospheres uniformly distribute at the SnO2/perovskite interface and a larger grain and more uniform perovskite film is obtained due to the increased contact angle. Moreover, Tz-GDY nanospheres can reduce the fermi energy level to facilitate the electron injection. Consequently, the Tz-GDY modified PSCs exhibits a champion power conversion efficiency of 24.83 % with effectively suppressed hysteresis. Our strategy proposes a more efficient electron collection method in buried interface, providing a guidance for constructing efficient PSCs.

In silico evaluation of favipiravir-associated potential new drugs against polymerase enzyme of SARS-CoV-2

Millions of lives have been lost to the deadly SARS-CoV-2 virus. Vaccines and antiviral drugs are essential scientific tools in combating viral infections. This in silico study focused on the RdRp inhibitor favipiravir, exploring new analogs by substituting the fluorine atom on the pyrazine ring with both homocyclic and heterocyclic moieties. Initially, ADME and toxicity properties were assessed using SwissADME and ProTox-II online tools. Ligands L6 and L7 exhibited high bioavailability and drug-likeness compared to favipiravir. Subsequently, all new analogs were docked into the RdRp active site using AutoDock Vina, demonstrating high affinity compared to favipiravir. Based on optimal ADMET profiles and docking scores, ligands L4, L6, and L7 underwent 200 ns MDS using the CHAARM 36 force field in NAMD software to validate docking results. Various trajectory analyses, including RMSD, RMSF, histograms, total number of contacts, and ligand properties, were conducted to gain insights into the interaction patterns between ligands and RdRp. All protein-ligand complexes exhibited greater stability than favipiravir throughout simulations period. This theoretical study suggests that ligands L6 and L7 could serve as lead candidates for RdRp inhibition. Cell-Based SARS-CoV-2 RdRp Activity Assay is recommended to validate these in silico findings.

Spectral-luminescence properties of PV corrolazines with axial alkoxide ligands

New phosphorus(V) complexes of octaphenyl substituted tetrapyrazinocorrolazines (TPyzCA) containing in the axial positions alkoxide ligands [TPyzCAP(OC2H4X)2] (X = Pr, NMe2, OH) were synthesized using the one-pot procedure and effect of acid on their spectral luminescence and photochemical properties was studied. The presence of fused pyrazine rings increases the ability to bind axial ligands compared to benzo-fused corrolazine (TBzCA). Excited state properties are strongly dependent on the solvation effects. The effect of excited state quenching by photoinduced electron transfer is observed only for the dimethylaminoethoxide complex of TPyzCA in polar solvents, like THF or DMSO. Still, it is absent in dichloromethane, toluene, and for TBzCA derivatives. The hydroxyethoxide complex of TPyzCA and dimethylaminoethoxide complex of TBzCA exhibit efficient fluorescence and high singlet oxygen generation ability in DMSO solution.

Cancer Therapy with Quinoxaline Derivatives: Dual Inhibition of Pi3k and Mtor Signaling Pathways

Quinoxaline is a heterocyclic compound with a benzene ring fused to a pyrazine ring. It learned much about his ability to cure many diseases, including cancer. Phosphoinositide 3kinase (PI3K) and the mTOR (mammalian target of rapamycin) are the 3 essential pathways which regulate the growth, survival, and development of cells. Dysregulation of such pathways is often seen in cancer, making them attractive targets for cancer therapy. In particular, several quinoxaline derivatives show promise as two inhibitors of the mTOR/PI3K signalling pathway, which is often dysregulated in cancer along with many other diseases. One such example is PX866, which has shown activity against several cancers in previous studies. In previous studies, another quinoxaline derivative, PKI587, also showed strong inhibitory activity against mTOR and PI3K. PKI587 was researched in several clinical trials for treating many cancer types, which include non-small cell lung as well as breast cancer. Dual inhibitors of mTOR and PI3K, including quinoxaline derivatives, inhibit cell growth and cancer by blocking the signalling of these two important factors. In recent years, quinoxaline derivatives have emerged as potent dual inhibitors of PI3K and mTOR, and in this review, we explore the latest developments in this area.

Investigation of substituent effects on the electronic structure and antiviral activity of favipiravir derivatives for Covid-19 treatment using DFT and molecular docking

In this study, Density-functional theory/Time-dependent density-functional theory (DFT/TDDFT) and Molecular docking method was used to investigate the effect of methyl acetate, tetrahydrofuran and cyanobenzylidene substituents on the electronic structure and antiviral activity of favipiravir for treating COVID-19. The DFT and TDDFT computations were employed using the Gaussian 09 software package. The values were calculated using the 6-311++G(d, p) basis set and the hybrid B3LYP functional method. Autodock vina software was used for simulations to better predictions and to validate the modified compounds' binding affinities and poses. Results of the study indicate that compounds 1 to 6 all displayed a planar structure, where the pyrazine ring, carboxamide, hydroxyl groups, and other substituents are all situated within the same plane. In addition, the energy gaps (Egap) of these six compounds (Cpd 1, 2, 3, 4, 5, and 6) were compared. The significant dipole moment and binding affinity achieved implies a particular orientation for binding within the target protein, signaling the anticipated strength of the binding interaction. In all six compounds, the electrophilic domain is situated in the vicinity of the amine functional group within the carboxamide compound, whereas the nucleophilic domain encompasses both the carbonyl and hydroxyl groups. The most negatively charged sites are susceptible to electrophilic interactions. In conclusion, compounds 5 and 6 exhibit a high binding affinity of the target protein, while compound 6 has a high energy gap, which could enhance its antiviral activity against the COVID-19 virus.

Synthesis, in silico and biodistribution studies of a novel 47Sc-radiolabeled α-amino acid ester derivative attached to pyrazine and tetrazole rings for tumor targeted radiotherapy

Abstract Recently, tumor-targeted radionuclide therapy has gained much recognition for the treatment of metastasized cancer. There is a growing interest in using the theranostic radionuclide 47Sc, owing to its excellent chemical and nuclear properties. However, the available chelating agents require a relatively high temperature for their radiolabeling, which could denature biomolecules. The aim of the present study is to synthesize a dipeptide agent that forms a thermodynamically more stable complex with 47Sc at room temperature. A novel α-amino acid ester derivative attached to pyrazine and tetrazole heterocyclic rings has been prepared by the azide coupling method. Different spectroscopic methods (FT-IR, 1H NMR, and mass spectra) were used for characterization of the target compound. The newly synthesized dipeptide was radiolabeled with 47Sc, and a high radiochemical yield of 98.5 ± 1.5 % and in vitro serum stability up to 72 h were attained at room temperature within 20 min. The quantum chemical calculations at B3PW91/6-31G(d) level were employed to establish the molecular structure of the dipeptide and its complexation with 47Sc. The selectivity of 47Sc-dipeptide toward localization in tumor cells was performed by molecular docking on different receptors in addition to in vivo biodistribution on solid tumor-bearing mice. A high T/NT ratio of 8.16 was obtained after 4 h p.i, suggesting that this complex could be used as a potential cancer theranostic agent.

Construction of a Bifunctional Redox-Site Conjugated Covalent-Organic Framework for Photoinduced Precision Trapping of Uranyl Ions.

The performance of covalent-organic frameworks (COFs) for the photocatalytic extraction of uranium is greatly limited by the number of adsorption sites. Herein, inspired by electronegative redox reactions, we designed a nitrogen-oxygen rich pyrazine connected COF (TQY-COF) with multiple redox sites as a platform for extracting uranium via combining superaffinity and enhanced photoinduction. The preorganized bisnitrogen-bisoxygen donor configuration on TQY-COF is entirely matched with the typical geometric coordination of hexavalent uranyl ions, which demonstrates high affinity (tetra-coordination). In addition, the presence of the carbonyl group and pyrazine ring effectively stores and controls electron flow, which efficaciously facilitates the separation of e-/h+ and enhances photocatalytic performance. The experimental results show that TQY-COF removes up to 99.8% of uranyl ions from actual uranium mine wastewater under the light conditions without a sacrificial agent, and the separation coefficient reaches 1.73 × 106 mL g-1 in the presence of multiple metal ions, which realizes the precise separation in the complex environment. Importantly, DFT calculations further elucidate the coordination mechanism of uranium and demonstrate the necessity of the presence of N/O atoms in the photocatalytic adsorption of uranium.

Synthesis and luminescent properties of a linear difluorene pyrazine (D-A-D) derivative as a selective indicator for a reversible acid-base vapour sensor

We have synthesized a structure in which pyrazine is the core structure and fluorene derivatives are attached to both sides. Photo physical investigations such as aprotic solvents (Hexane to DMF) were carried out. A redshift was revealed from non-polar aprotic solvents to polar aprotic solvents. The luminescence intensity was gradually decreased, which is incredibly more complex towards changes in the solvent polarization than their UV/Vis absorption spectra. The compound showed a redshift from 445 nm to 473 nm when slowly increasing the water fraction (fw) from 0 to 30 %. Also, rising water fraction (fw > 40–90 %) effectively attenuated the instantaneous emission intensity was observed. At the same time, the intensity of the emission peak was reduced due to the TICT effect on fluorene and pyrazine rings due to enhanced solvent polarity. In addition, optically reversible acidofluorochromic properties were performed experimentally in both solvent and solid phases. For the acidic substances TFA and HF, which contain fluorine, new redshift peaks from 425 nm and 503 nm were observed upon reaction with the PDF solution, and the emission intensity was extinguished by more than 90 % and 60 %, respectively. Upon addition of TFA up to 1500 equal, the PDF mixture suffered from 50 % lower energy absorption intensity. The 1H NMR spectrum confirmed the proposed mechanism (TFA/TEA, ON-OFF-ON). Therefore, the present work presents a novel approach to fabricating ON-OFF-ON active-pull pyrazine scaffolds that can be used in DSEgens, referred to as “ON-OFF-ON” fluorescent sensors, for multifunctional applications.

High‐Efficiency and Long‐Lifetime Near‐Infrared OLEDs Based on Iridium Complexes with Enhanced Horizontal Emitting Dipole Orientation

AbstractHigh‐efficiency and long‐lifetime near‐infrared (NIR) organic light‐emitting diodes (OLEDs) are rarely reported. Herein, three efficient NIR Ir(III) complexes 1–3 are developed with specially designed cyclometallated ligands based on pyrido[3,4‐b]pyrazine and oriented substitutions along the Ir─N bond axis. Electron‐deficient pyrazine ring effectively stabilizes LUMO energy, leading to significant emission bathochromic shift. Importantly, for complexes 2 and 3, oriented substitutions along the direction of the Ir─N bond axis considerably enhance the horizontal emitting dipole orientation ratio up to 90%. Their OLEDs demonstrate high maximum external quantum efficiencies (EQEs), negligible efficiency roll‐offs, superior radiance, and long lifetimes. The maximum EQEs and radiances of devices are 9.84% and 158 W Sr−1 m−2 at 725 nm for 1, 6.98% and 14.03 W Sr−1 m−2 at 760 nm for 2, and 12.49% and 18.94 W Sr−1 m−2 at 735 nm for 3, respectively. The device lifetime LT97 at 10 mA cm−2 is 453 h for complex 2, which sets a champion lifetime for NIR‐OLEDs. This work demonstrates that pyrido[3,4‐b]pyrazine is a desired building block for robust NIR emitting Ir(III) complexes, providing a superior paradigm to combine high efficiency, negligible roll‐off, and long device lifetime simultaneously toward practical applications.

Reactions of Diaminonaphthalenes with a Cage‐Opened C60 Derivative

AbstractThe reactions of cage‐opened C60 derivatives with aromatic diamines are known to cause an orifice‐enlargement in association with incorporating extended π‐systems. The present work focuses on 1,2‐, 2,3‐, and 1,8‐diaminonaphthalenes for the synthesis of a series of naphthalene‐fused fullerene derivatives. For the former two, orifice enlargement proceeded by cleaving two C=C bonds to afford an opening with a ring‐atom count of 20, in which the naphthalene moiety was fused by a pyrazine ring. For the reaction with 1,8‐diaminonaphthalene, only one C=C bond was cleaved to give a 17‐membered‐ring opening where the diaminonaphthalene moiety was fused by a pyrimidine ring.

Isothianaphthene quinoids: pyrazine-annelated structures for tuning electronic properties

Abstract The development of quinoidal systems with extended π-conjugation has elucidated the influence that diradical characteristics exert on structure–property relationships, which is significant because it broadens the possibilities for the use of organic semiconducting materials in organic electronics. However, the chain-length elongation of such quinoidal molecules has resulted in low chemical stability due to the large contribution of diradical characteristics and to the high level of the highest occupied molecular orbital (HOMO), both of which limit the synthesis of π-extended quinoidal molecules. Here, we describe solving this problem via aromatic stabilization. To accomplish this, we designed a system that utilizes electron-accepting pyrazine-fused thieno[3,4-b]pyrazine following the development of the isothianaphthene quinoids of thiophene 3-mer and 6-mer. Theoretical calculations indicate that the introduction of a pyrazine-annelated structure suppresses the diradical characteristics and stabilizes the HOMO energy level of quinoidal oligothiophenes. The thermal, photophysical, and physicochemical properties of newly synthesized quinoidal molecules with full annelation of the benzene and pyrazine rings were investigated. Quinoidal thiophene 3-mer functioned as an acceptor in organic solar cells with a power conversion efficiency of 1.04%. This study demonstrates that the introduction of pyrazine-fused rings is an effective molecular design to extend the chain length of quinoidal oligothiophenes.

Interaction and Binding Kinetics of Different Substituted Pyrazines with HSA: Based on Multispectral, Physiological Activity, and Molecular Dynamics Simulations

Pyrazine is a kind of compound containing pyrazine ring structure, which has attracted the attention of researchers because of its special aroma and healthcare function. It is currently used in spices, pharmaceuticals, food additives, and other industries. Human serum albumin (HSA) is a transport and storage protein in the human circulatory system. Previous research reported that pyrazine can interact with albumin, but the interaction between pyrazine and HSA has not been reported. Consequently, this study is based on the multispectral method and molecular dynamics (MD) simulation, exploring the interaction between different pyrazines and HSA. The results show that the four pyrazines mainly quench the endogenous fluorescence of HSA through the static quenching mechanism. Molecular docking indicates that hydrophobic forces play a major role in the binding of pyrazines with HSA. At the same time, synchronous fluorescence spectroscopy, circular dichroism (CD), three-dimensional fluorescence spectroscopy, and resonance light scattering (RLS) showed that each pyrazine compound can change the conformation of HSA. MD simulation results show that the combination of four pyrazines and HSA can enhance the stability of HSA. Among them, 2,3,5,6-tetramethylpyrazine (TTMP) and 2,3,5-trimethylpyrazine (TMTP) binding is the most stable and the most unstable combination with HSA, respectively. In addition, the four pyrazines could affect the physiological activity of HSA. This study is of great significance to explore the mechanism of action of pyrazine compounds in vivo and can provide useful information for the application of pyrazine compounds in food.

Water-soluble dye – ZnII octacarboxy substituted tetrapyrazinoporphyrazine: Spectral-luminescence study of behavior in aqueous solutions

ZnII complex of octacarboxy substituted tetrapyrazinoporohyrazine, ZnTPyzPA(COOH)8, was prepared by mild alkaline hydrolysis of the corresponding octaethyl ester, ZnTPyzPA(COOEt)8, which was synthesized by template cycloteramerization of 5,6-di(ethoxycarbonyl)pyrazine-2,3-dicarbonitrile in the presence zinc(II) acetate in o-dichlorobenzene. Both complexes were characterized by IR, UV–vis, NMR spectroscopy (1H, 13C). Conformational analysis performed by DFT method in agreement with spectral study indicates that one of COOH group in each pyrazine ring participates in intramolecular hydrogen bonding with the adjacent pyrazine nitrogen atom. Unlike octacarboxy substituted ZnII phthalocyanine, ZnTPyzPA(COOH)8 remains non-aggregated not only in the octaanionic form present in the basic medium but also in tetraanioinic form existing in acid aqueous solutions since intramolecular H-bonding prevents intermolecular interactions. However, the fluorescence is almost completely quenched for tetraanion which can be related to the proton transfer in the excited state from carboxylic group to the pyrazine nitrogen. Aggregation is observed only for non-ionized form of ZnTPyzPA(COOH)8 existing in strongly acidic medium (1 M HCl solution, pH < 1).

Effects of pyrazine and its derivatives as inhibitors on copper film chemical-mechanical polishing properties for ruthenium-based copper interconnect

During the one-step chemical mechanical polishing (CMP) process of ruthenium (Ru)-based copper (Cu) interconnected Cu films, a high Cu removal rate (RR) while maintaining a near zero Ru RR should be required to ensure a flat surface. The most ideal and difficult part of the CMP process is how to achieve rapid removal of Cu film without affecting Ru layer. Corrosion inhibitors in the slurry fulfill a significant function in controlling RR and improving the surface quality. Therefore, in this study, pyrazine (PY) and its derivative aminopyrazine (AP) as cost-effective and harmless corrosion inhibitors for Ru-based Cu interconnected Cu film CMP were investigated under weakly alkaline conditions (pH=8.5). First, through the utilization of experimental and theoretical methods, a systematical analysis was conducted to assess the corrosion inhibition effects of AP and PY, and it was found that the corrosion inhibition effect of AP was stronger than that of PY. Then, the adsorption and inhibition mechanism of AP on Cu/Ru surface were analyzed by electrochemical testing and X-ray photoelectron spectroscopy (XPS), and the adsorption behavior of AP molecules on the Cu (111) surface was investigated at the molecular level using quantum chemical methods. Finally, tests on Cu patterned wafers showed that the combination of 0.5 wt% AP and 0.5 wt% sarcosine (Sar) proved to be successful in effectively rectifying the step height on the Cu patterned wafer. At the same time, a high RR of 7281 Å /min, a low surface root mean square deviation (Sq) of 1.35 nm in 10 μm×10 μm region and a low static etching rate (SER) of 1015 Å /min were obtained with the synergistic effect of AP and Sar. This outcome holds substantial theoretical implications for advancing the formulation of low-node Cu film slurry.

Stabilizing Azaheptacenes.

The symmetrical 7,16-diaza-6,8,15,17-tetrakis(triisopropylsilylethynyl)heptacene was obtained by a Pd-catalyzed reaction of a 2,3-diamino-1,4-diethynylanthracene with a 2,3-dibromo-1,4-diethynyl anthracene. Positioning the TIPS-ethynyl groups adjacent to the central ring suppresses dimerization via [4+4] cycloadditions and Diels-Alder reactions; the middle pyrazine ring renders this species stable to oxidation. A single crystal structure was obtained, and thin film transistors with μn = 0.042 cm2 V-1 s-1 were produced. Transposition of the alkynyl groups into the 5,8,15,18-positions with a quinoxaline unit in the center of the heptacene decreases the stability, as does the introduction of two more nitrogen atoms into the 5,18-positions. The hydrocarbon 6,8,15,17-tetrakis(triisopropylsilylethynyl)heptacene is reasonably stable with a half-life of 25 h in solution. Four correctly placed TIPS-ethynyl groups protect heptacene cores.