Maddess, Matthew L.’s team published research in Organometallics in 2019 | CAS: 128071-75-0

2-Bromonicotinaldehyde(cas: 128071-75-0) belongs to pyridine. Pyridine is a relatively complex molecule and exhibits a number of different bands in IR spectra. Among others, the bands characterizing the ν8a and ν19b modes have been found to be sensitive to the coordination or protonation of the molecule. Note that the band that is diagnostic for the PyH+ ion at about 1545 cm− 1 (ν19b mode) does not overlap with any of the other bands.Quality Control of 2-Bromonicotinaldehyde

The author of 《Metal Catalyzed Synthesis of Dihydropyridobenzodiazepines》 were Maddess, Matthew L.; Li, Chaomin. And the article was published in Organometallics in 2019. Quality Control of 2-Bromonicotinaldehyde The author mentioned the following in the article:

A versatile synthesis of dihydropyridobenzodiazepines that proceeds via a palladium-catalyzed C-N coupling and catalytic hydrogenation cascade is reported. The intermediate 2-anilinonicotinaldehydes may be efficiently protected to ultimately afford N6 differentiated dihydropyridobenzodiazepines, which facilitates further elaboration. The experimental process involved the reaction of 2-Bromonicotinaldehyde(cas: 128071-75-0Quality Control of 2-Bromonicotinaldehyde)

2-Bromonicotinaldehyde(cas: 128071-75-0) belongs to pyridine. Pyridine is a relatively complex molecule and exhibits a number of different bands in IR spectra. Among others, the bands characterizing the ν8a and ν19b modes have been found to be sensitive to the coordination or protonation of the molecule. Note that the band that is diagnostic for the PyH+ ion at about 1545 cm− 1 (ν19b mode) does not overlap with any of the other bands.Quality Control of 2-Bromonicotinaldehyde

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Dhiman, Nisha’s team published research in New Journal of Chemistry in 2019 | CAS: 141-86-6

2,6-Diaminopyridine(cas: 141-86-6) belongs to pyridine. Pyridine and its simple derivatives are stable and relatively unreactive liquids, with strong penetrating odours that are unpleasant.Safety of 2,6-Diaminopyridine

The author of 《A nitrogen and phosphorus enriched pyridine bridged inorganic-organic hybrid material for supercapacitor application》 were Dhiman, Nisha; Mohanty, Paritosh. And the article was published in New Journal of Chemistry in 2019. Safety of 2,6-Diaminopyridine The author mentioned the following in the article:

A new class of N- and P-enriched pyridine bridged inorganic-organic hybrid material is synthesized via the condensation of phosphonitrilic chloride trimer and 2,6-diaminopyridine at 140°C for 18 h. It was used as the active electrode material for supercapacitor application. The role of mass loading on the overall performance of the HPHM supercapacitor electrode has been investigated. Specific capacitances of 243 and 107 F g-1 are estimated from cyclic voltammetry and galvanostatic charge-discharge measurements at a scan rate of 1 mV s-1 and c.d. of 0.5 A g-1, resp. The high retention of 81% of the initial Csp value is observed after 2000 cycles at a c.d. of 5 A g-1. A fabricated solid-state sym. supercapacitor device made with the optimal mass loading shows power and energy densities of 244 W kg-1 and 14.4 W h kg-1, resp., and it could light up a green LED display (23 in total) for up to 50 s upon charging for 5 s at 3 V. After reading the article, we found that the author used 2,6-Diaminopyridine(cas: 141-86-6Safety of 2,6-Diaminopyridine)

2,6-Diaminopyridine(cas: 141-86-6) belongs to pyridine. Pyridine and its simple derivatives are stable and relatively unreactive liquids, with strong penetrating odours that are unpleasant.Safety of 2,6-Diaminopyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Kim, Seung Min’s team published research in ACS Infectious Diseases in 2020 | CAS: 624-28-2

2,5-Dibromopyridine(cas: 624-28-2) belongs to pyridine. In industry and in the lab, pyridine is used as a reaction solvent, particularly when its basicity is useful, and as a starting material for synthesizing some herbicides, fungicides, and antiseptics.Formula: C5H3Br2N

《Phenotypic Discovery of an Antivirulence Agent against Vibrio vulnificus via Modulation of Quorum-Sensing Regulator SmcR》 was published in ACS Infectious Diseases in 2020. These research results belong to Kim, Seung Min; Park, Jongmin; Kim, Myun Soo; Song, Heebum; Jo, Ala; Park, Hankum; Kim, Tae Sung; Choi, Sang Ho; Park, Seung Bum. Formula: C5H3Br2N The article mentions the following:

An antivirulence agent against Vibrio vulnificus named quoromycin (QM, I) was discovered by a phenotype-based elastase inhibitor screening. Using the fluorescence difference in two-dimensional gel electrophoresis (FITGE) approach, SmcR, a quorum-sensing master regulator and homolog of LuxR, was identified as the target protein of QM. We confirmed that the direct binding of QM to SmcR inhibits the quorum-sensing signaling pathway by controlling the DNA-binding affinity of SmcR and thus effectively alleviates the virulence of V. vulnificus in vitro and in vivo. I can be regarded as a novel antivirulence agent for the treatment of V. vulnificus infection. In the part of experimental materials, we found many familiar compounds, such as 2,5-Dibromopyridine(cas: 624-28-2Formula: C5H3Br2N)

2,5-Dibromopyridine(cas: 624-28-2) belongs to pyridine. In industry and in the lab, pyridine is used as a reaction solvent, particularly when its basicity is useful, and as a starting material for synthesizing some herbicides, fungicides, and antiseptics.Formula: C5H3Br2N

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Miller, Kelsey R.’s team published research in Inorganic Chemistry in 2020 | CAS: 1539-42-0

Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0) is a secondary amine with two picolyl substituents. As a tridentate ligand this compound provides three nitrogen donors that affords good selectivity for Zn2+ over biologically relevant metals such as Na+, K+, Mg2+ and Ca2+, and leaves coordination sites free for anion binding. Name: Bis(pyridin-2-ylmethyl)amine

《Artificial Iron Proteins: Modeling the Active Sites in Non-Heme Dioxygenases》 was published in Inorganic Chemistry in 2020. These research results belong to Miller, Kelsey R.; Paretsky, Jonathan D.; Follmer, Alec H.; Heinisch, Tillmann; Mittra, Kaustuv; Gul, Sheraz; Kim, In-Sik; Fuller, Franklin D.; Batyuk, Alexander; Sutherlin, Kyle D.; Brewster, Aaron S.; Bhowmick, Asmit; Sauter, Nicholas K.; Kern, Jan; Yano, Junko; Green, Michael T.; Ward, Thomas R.; Borovik, A. S.. Name: Bis(pyridin-2-ylmethyl)amine The article mentions the following:

An important class of non-heme dioxygenases contains a conserved Fe binding site that consists of a 2-His-1-carboxylate facial triad. Results from structural biol. show that, in the resting state, these proteins are six-coordinate with aqua ligands occupying the remaining three coordination sites. We have utilized biotin-streptavidin (Sav) technol. to design new artificial Fe proteins (ArMs) that have many of the same structural features found within active sites of these non-heme dioxygenases. An Sav variant was isolated that contains the S112E mutation, which installed a carboxylate side chain in the appropriate position to bind to a synthetic FeII complex confined within Sav. Structural studies using X-ray diffraction (XRD) methods revealed a facial triad binding site that is composed of two N donors from the biotinylated ligand and the monodentate coordination of the carboxylate from S112E. Two aqua ligands complete the primary coordination sphere of the FeII center with both involved in hydrogen bond networks within Sav. The corresponding FeIII protein was also prepared and structurally characterized to show a six-coordinate complex with two exogenous acetato ligands. The FeIII protein was further shown to bind an exogenous azido ligand through replacement of one acetato ligand. Spectroscopic studies of the ArMs in solution support the results found by XRD. Biol. O2 activation is often accomplished with dioxygenases that contain non-heme iron centers with a common 2-His-1-carboxylate endogenous binding site for iron. We have engineered an artificial protein to model this site using biotin-streptavidin technol. Structural and spectroscopic studies support formation of an Fe(II) artificial protein with features similar to those in the native proteins, including hydrogen bonds within the secondary coordination sphere. This work highlights the utility of embedding metal complexes with protein hosts.Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0Name: Bis(pyridin-2-ylmethyl)amine) was used in this study.

Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0) is a secondary amine with two picolyl substituents. As a tridentate ligand this compound provides three nitrogen donors that affords good selectivity for Zn2+ over biologically relevant metals such as Na+, K+, Mg2+ and Ca2+, and leaves coordination sites free for anion binding. Name: Bis(pyridin-2-ylmethyl)amine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Ling, Xiang’s team published research in Science China: Chemistry in 2020 | CAS: 53939-30-3

5-Bromo-2-chloropyridine(cas: 53939-30-3) belongs to pyridine. In industry and in the lab, pyridine is used as a reaction solvent, particularly when its basicity is useful, and as a starting material for synthesizing some herbicides, fungicides, and antiseptics.Application In Synthesis of 5-Bromo-2-chloropyridine

《A visible-light-photocatalytic water-splitting strategy for sustainable hydrogenation/deuteration of aryl chlorides》 was published in Science China: Chemistry in 2020. These research results belong to Ling, Xiang; Xu, Yangsen; Wu, Shaoping; Liu, Mofan; Yang, Peng; Qiu, Chuntian; Zhang, Guoqiang; Zhou, Hongwei; Su, Chenliang. Application In Synthesis of 5-Bromo-2-chloropyridine The article mentions the following:

Abstract: Hydrogenation/deuteration of carbon chloride (C-Cl) bonds is of high significance but remains a remarkable challenge in synthetic chem., especially using safe and inexpensive hydrogen donors. In this article, a visible-light-photocatalytic water splitting hydrogenation technol. (WSHT) is proposed to in-situ generate active H-species (i.e., Had) for controllable hydrogenation of aryl chlorides instead of using flammable H2. When applying heavy water-splitting systems, we could selectively install deuterium at the C-Cl position of aryl chlorides under mild conditions for the sustainable synthesis of high-valued added deuterated chems. Sub-micrometer Pd nanosheets (Pd NSs) decorated crystallined polymeric carbon nitrides (CPCN) is developed as the bifunctional photocatalyst, whereas Pd NSs not only serve as a cocatalyst of CPCN to generate and stabilize H (D)-species but also play a significant role in the sequential activation and hydrogenation/deuteration of C-Cl bonds. This article highlights a photocatalytic-WSHT for controllable hydrogenation/deuteration of low-cost aryl chlorides, providing a promising way for the photosynthesis of high-valued added chems. instead of the hydrogen evolution. After reading the article, we found that the author used 5-Bromo-2-chloropyridine(cas: 53939-30-3Application In Synthesis of 5-Bromo-2-chloropyridine)

5-Bromo-2-chloropyridine(cas: 53939-30-3) belongs to pyridine. In industry and in the lab, pyridine is used as a reaction solvent, particularly when its basicity is useful, and as a starting material for synthesizing some herbicides, fungicides, and antiseptics.Application In Synthesis of 5-Bromo-2-chloropyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Ahmed, Nadeem’s team published research in Journal of Fluorescence in 2020 | CAS: 1539-42-0

Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0) is a secondary amine with two picolyl substituents. As a tridentate ligand this compound provides three nitrogen donors that affords good selectivity for Zn2+ over biologically relevant metals such as Na+, K+, Mg2+ and Ca2+, and leaves coordination sites free for anion binding. HPLC of Formula: 1539-42-0

《Coumarin-Based Reversible Fluorescent Probe for Selective Detection of Cu2+ in Living Cells》 was published in Journal of Fluorescence in 2020. These research results belong to Ahmed, Nadeem; Zareen, Wajeeha; Zhang, Di; Yang, Xiaopeng; Ye, Yong. HPLC of Formula: 1539-42-0 The article mentions the following:

Abstract: Copper ion plays an important role in many biol. processes in human body. H2S is considered as the third gasses transmitter after carbon monoxide and nitric oxide. Here a novel ICT-based fluorescent ON-OFF-ON probe for Cu2+ and H2S detection was developed. Selectivity and sensitivity of probe was confirmed in aqueous Tris-HCl buffer (10 mM, pH 7.4, containing 90% acetonitrile). Probe DF-CU shows high selectivity over other analytes. The degree of fluorescence quenching is linearly associated with the concentration of Cu2+ (R2 = 0.9919). The limit of detection (LOD, calculated according to the 3σ/slope) for Cu2+ was 6.4μM. Probe can work in almost all pH. The probe shows a very fast response to Cu2+ (within 10 s). Its response to copper ion could be reversed by H2S. The complex of probe with Cu2+ could be used for H2S detection. Furthermore, this ON-OFF-ON fluorescent probe successfully applied in the living cells for the detection of Cu2+ and H2S. In addition to this study using Bis(pyridin-2-ylmethyl)amine, there are many other studies that have used Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0HPLC of Formula: 1539-42-0) was used in this study.

Bis(pyridin-2-ylmethyl)amine(cas: 1539-42-0) is a secondary amine with two picolyl substituents. As a tridentate ligand this compound provides three nitrogen donors that affords good selectivity for Zn2+ over biologically relevant metals such as Na+, K+, Mg2+ and Ca2+, and leaves coordination sites free for anion binding. HPLC of Formula: 1539-42-0

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Feng, Tianchi’s team published research in Chinese Chemical Letters in 2020 | CAS: 624-28-2

2,5-Dibromopyridine(cas: 624-28-2) belongs to pyridine. Pyridines are often used as catalysts or reagents; particular notice has been paid recently to how pyridine coordinates to metal centers enabling a wide range of valuable reactions. Quality Control of 2,5-Dibromopyridine

《Cavity-directed nitroaromatics sensing within a carbazole-based luminescent supramolecular M2L3 cage》 was published in Chinese Chemical Letters in 2020. These research results belong to Feng, Tianchi; Li, Xuezhao; Wu, Jinguo; He, Cheng; Duan, Chunying. Quality Control of 2,5-Dibromopyridine The article mentions the following:

The design and preparation of luminescent M2L3 metal-organic cage via the coordination-driven self-assembly of carbazole-based ligand with a V-shaped geometry is described. The cage Zn-L1 with an open cavity which equipped aromatic rich ligands shows the highest emission quenching efficiency towards picric acid than other nitroarom. explosives. The quenching ability depended on whether there formed the host-guest mols. are well explored by electrospray ionization mass spectrometry (ESI-MS), and isothermal titration microcalorimetry (ITC). The results came from multiple reactions, including the reaction of 2,5-Dibromopyridine(cas: 624-28-2Quality Control of 2,5-Dibromopyridine)

2,5-Dibromopyridine(cas: 624-28-2) belongs to pyridine. Pyridines are often used as catalysts or reagents; particular notice has been paid recently to how pyridine coordinates to metal centers enabling a wide range of valuable reactions. Quality Control of 2,5-Dibromopyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Wellm, Carsten’s team published research in Crystal Growth & Design in 2020 | CAS: 100-48-1

4-Cyanopyridine(cas: 100-48-1) belongs to pyridine. Pyridine is a relatively complex molecule and exhibits a number of different bands in IR spectra. Among others, the bands characterizing the ν8a and ν19b modes have been found to be sensitive to the coordination or protonation of the molecule. Note that the band that is diagnostic for the PyH+ ion at about 1545 cm− 1 (ν19b mode) does not overlap with any of the other bands.Quality Control of 4-Cyanopyridine

《Structural Variety in Mn(NCS)2 4-Cyanopyridine Coordination Compounds: Synthesis, Structures, Isomerism, and Magnetic Properties》 was written by Wellm, Carsten; Neumann, Tristan; Gallo, Gianpiero; Dziubyna, Anna M.; Rams, Michal; Dinnebier, Robert E.; Naether, Christian. Quality Control of 4-Cyanopyridine And the article was included in Crystal Growth & Design in 2020. The article conveys some information:

The reaction of Mn(NCS)2 with 4-cyanopyridine (CNpy) gives discrete complexes [Mn(NCS)2(CNpy)4] (1), [Mn(NCS)2(H2O)2(CNpy)2] (2-I and 2-II), and [Mn(NCS)2(H2O)2(CNpy)2]·xCNpy (x = 4, 3; x = 2, 4), in which the Mn(II) centers are octahedrally coordinated by two terminal N-bonded thiocyanate anions and by four (1) or two CNpy coligands and two H2O mols. (2-I, 2-II, 3, and 4). If an excess of Mn(NCS)2 was used, [Mn(NCS)2(CNpy)2]n (5) and [Mn(NCS)2(CNpy)]n (6-I and 6-II) were obtained. In all compounds the Mn(II) cations are octahedrally coordinated and linked into linear chains (5), into layers (6-I), or into a 3-dimensional network (6-II) by the thiocyanate anions. Studies using TG-DTA and temperature-dependent powder x-ray diffraction prove that the discrete complexes 2-II, 3, and 4 decompose in several steps, giving Mn(NCS)2 via 5 and 6-I as intermediates. For compounds 2-II, 4, and 6-II only one batch was obtained, indicating that these compounds are metastable. Magnetic measurements for 5 and 6-I reveal dominating antiferromagnetic interactions and susceptibility curve maxima at 20 K (5) and 24 K (6-I), reproduced by quantum Monte Carlo simulations. The sp. heat proves magnetic ordering at 2.8 K (5) and 12.4 K (6-I). The ordering of 6-I is associated with a weak ferromagnetism. Several Mn(NCS)2 4-cyanopyridine coordination compounds including polymorphic and isomeric modifications were synthesized and structurally characterized by SC-XRD and PXRD. Their thermal reactivity and magnetic behavior were studied. After reading the article, we found that the author used 4-Cyanopyridine(cas: 100-48-1Quality Control of 4-Cyanopyridine)

4-Cyanopyridine(cas: 100-48-1) belongs to pyridine. Pyridine is a relatively complex molecule and exhibits a number of different bands in IR spectra. Among others, the bands characterizing the ν8a and ν19b modes have been found to be sensitive to the coordination or protonation of the molecule. Note that the band that is diagnostic for the PyH+ ion at about 1545 cm− 1 (ν19b mode) does not overlap with any of the other bands.Quality Control of 4-Cyanopyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Liu, Xixi’s team published research in Arabian Journal of Chemistry in 2020 | CAS: 100-48-1

4-Cyanopyridine(cas: 100-48-1) belongs to pyridine. When pyridine is adsorbed on oxide surfaces or in porous materials, the following species are commonly observed: (i) pyridine coordinated to Lewis acid sites, (ii) pyridine H-bonded to weakly acidic hydroxyls, and (iii) protonated pyridine. At high coverage, physisorbed pyridine and protonated dimers can also be observed.Recommanded Product: 100-48-1

《High performance of nitrogen-doped carbon-supported cobalt catalyst for the mild and selective synthesis of primary amines》 was written by Liu, Xixi; Wang, Yanxin; Jin, Shiwei; Li, Xun; Zhang, Zehui. Recommanded Product: 100-48-1 And the article was included in Arabian Journal of Chemistry in 2020. The article conveys some information:

A nitrogen-doped carbon-supported Co catalyst (Co/N-C-800) was discovered to be highly active for the reductive amination of carbonyl compounds with NH3 and the hydrogenation of nitriles into primary amines using H2 as the hydrogen source. Structurally diverse carbonyl compounds were selectively transformed into primary amines with good to excellent yields (82.8-99.6%) under mild conditions. The Co/N-C-800 catalyst showed comparable or better catalytic performance than the reported noble metal catalysts. The Co/N-C-800 catalyst also showed high activity for the hydrogenation of nitriles, affording the corresponding primary amines with high yields (81.7-99.0%). An overall reaction mechanism is proposed for the reductive amination of benzaldehyde and the hydrogenation of benzonitrile, which involves the same intermediates of phenylmethanimine and N-benzylidenebenzylamine. After reading the article, we found that the author used 4-Cyanopyridine(cas: 100-48-1Recommanded Product: 100-48-1)

4-Cyanopyridine(cas: 100-48-1) belongs to pyridine. When pyridine is adsorbed on oxide surfaces or in porous materials, the following species are commonly observed: (i) pyridine coordinated to Lewis acid sites, (ii) pyridine H-bonded to weakly acidic hydroxyls, and (iii) protonated pyridine. At high coverage, physisorbed pyridine and protonated dimers can also be observed.Recommanded Product: 100-48-1

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Knedel, Tim-Oliver’s team published research in Inorganic Chemistry in 2020 | CAS: 626-05-1

2,6-Dibromopyridine(cas: 626-05-1) belongs to pyridine. Pyridine derivatives lend themselves to many roles in the spirited field of supramolecular chemistry – whether as the ligand backbone of metal-organic polymers or presiding over the key electronic stations of nanodevices. In biochemistry, pyridine-containing cofactors are necessary nutrients on which our lives depend. Name: 2,6-Dibromopyridine

《Encapsulation of Phosphorescent Pt(II) Complexes in Zn-Based Metal-Organic Frameworks toward Oxygen-Sensing Porous Materials》 was written by Knedel, Tim-Oliver; Buss, Stefan; Maisuls, Ivan; Daniliuc, Constantin G.; Schluesener, Carsten; Brandt, Philipp; Weingart, Oliver; Vollrath, Annette; Janiak, Christoph; Strassert, Cristian A.. Name: 2,6-Dibromopyridine And the article was included in Inorganic Chemistry in 2020. The article conveys some information:

In this work, two tailored phosphorescent Pt(II) complexes are synthesized bearing a cyclometalating tridentate thiazole-based C^N*N pincer luminophore (L) and exchangeable chlorido ([PtCl(L)]) or cyanido ([PtCN(L)]) coligands. While both complexes showed photoluminescence from metal-perturbed ligand-centered triplet states (3MP-LC), [PtCN(L)] reached the highest phosphorescence quantum yields and displayed a significant sensitivity toward quenching by 3O2. They were encapsulated into two Zn-based metal-organic frameworks, namely, MOF-5 and ZIF-8. The incorporation of the organometallic compounds in the resulting composites [PtCl(L)]@ZIF-8, [PtCN(L)]@ZIF-8, [PtCl(L)]@MOF-5 and [PtCN(L)]@MOF-5 was verified by powder X-ray diffractometry, SEM, time-resolved photoluminescence spectroscopy and microscopy, as well as N2- and Ar-gas sorption studies. The amount of encapsulated complex was determined by graphite furnace at. absorption spectroscopy, showing a maximum loading of 3.7 wt %. If compared with their solid state forms, the solid-solution composites showed prolonged 3O2-sensitive excited state lifetimes for the complexes at room temperature, reaching up to 18.4μs under an Ar atm., which is comparable with the behavior of the complex in liquid solutions or even frozen glassy matrixes at 77 K. Two tailored phosphorescent Pt(II) complexes were synthesized bearing a cyclometalating tridentate thiazole-based C^N*N pincer luminophore and exchangeable coligands. They were encapsulated into two Zn-based metal-organic frameworks, namely, MOF-5 and ZIF-8. If compared with their liquid solutions, the solid-solution composites showed prolonged 3O2-sensitive excited state lifetimes for the complexes at room temperature, reaching up to 18.4μs under an Ar atm., which is comparable with the behavior of the complex in frozen glassy matrixes at 77 K.2,6-Dibromopyridine(cas: 626-05-1Name: 2,6-Dibromopyridine) was used in this study.

2,6-Dibromopyridine(cas: 626-05-1) belongs to pyridine. Pyridine derivatives lend themselves to many roles in the spirited field of supramolecular chemistry – whether as the ligand backbone of metal-organic polymers or presiding over the key electronic stations of nanodevices. In biochemistry, pyridine-containing cofactors are necessary nutrients on which our lives depend. Name: 2,6-Dibromopyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem