Excited-State Intramolecular Proton Transfer in Five-Membered Hydrogen-Bonding Systems:  2-Pyridyl Pyrazoles

Yu, Wei-Shan; Cheng, Chung-Chih; Cheng, Yi‐Ming; Wu, Po-Chang; Song, Yi-Hwa; Chi, Yun; Chou, Pi‐Tai

doi:10.1021/ja035382y

Cited by 169 publications

(110 citation statements)

References 6 publications

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“…Recently, the proton transfer in the solid state has been communicated for this group of materials [2]. Pyrazoles crystallize with four hydrogen bonding patterns like: dimers, trimers, tetramers and catemers throngh N-H···Nh ydrogen interactions using both Natoms of the pyrazole [3].…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 3-(furan-2-yl)-5-(4-methoxyphenyl)-1H-pyrazole, C14H12N2O2

Zheng¹,

Sun²

2010

Zeitschrift Für Kristallographie - New Crystal Structures

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Section: Discussionmentioning

confidence: 99%

Crystal structure of 3-(furan-2-yl)-5-(4-methoxyphenyl)-1H-pyrazole, C14H12N2O2

Zheng¹,

Sun²

2010

Zeitschrift Für Kristallographie - New Crystal Structures

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“…Pyrazoles which crystallized with four hydrogen-bonding patterns: dimers, trimers, tetramers and catemers throngh N−H···Nh ydrogen interactions using both N atoms of the pyrazole, have received much more interesting in their crystals [3,4]. The crystal structure analysis shows that the title molecules contain two independent pyrazole molecules and two MeOH molecules in the asymmetric unit (figure, top).…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 3-(furan-2-yl)-5-(4-phenylphenyl)-1H-pyrazole — methanol (1:1), C19H14N2O · CH3OH

Zheng¹,

Sun²

2010

Zeitschrift Für Kristallographie - New Crystal Structures

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C 20 H 18 N 2 O 2 ,triclinic, P1 (no. 2), a =10.362(2) Å, b =13.023(2) Å, c =13.641(2) Å, a =74.455(3)°, Source of materialHydrazine monohydrate (3 ml) in ethanol (10 ml) was added dropwise to arefluxing ethanol solution (30 ml) of the 1-(furan-2-yl)-3-(4-phenylphenyl)propane-1,3-dione (2.90 .g). The solution was refluxed for 3hand solvents were removed by evaporation.The residual solid was recrystallized from dillute ethanol solution to give the title compound (yield 2.12 g, 74 %). Crystals suitable for X-ray diffraction were grown by slow evaporation of the CH 2 Cl 2 /MeOH (1:2, v/v)solutions at room temperature. Experimental detailsHa toms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with d(C-H) of 0.93 to 0.97 Å,and with U iso (H) =1.2 U eq (C). All Hatoms on Natoms were found in difference Fourier and refined with U iso (H) =1.2 U eq (N). No additional disordered solvent molecules were found applying PLATON procedure. The high residual values are caused by the poor quality of the selected crystal.

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“…Pyrazoles crystallize with four hydrogen-bonding patterns -dimers, trimers, tetramers and catemers through N−H···Nhydrogen interactions using both Natoms of the pyrazole [3,4]. In the title crystal structure the molecule adopts aH -bonded catemer structure.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 3-(furan-2-yl)-5-(naphthalen-6-yl)-1H-pyrazole, C17H12N2O

Zheng¹,

Sun²

2009

Zeitschrift Für Kristallographie - New Crystal Structures

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C 17 H 12 N 2 O, monoclinic, P12 1 /n1(no. 14), a =14.484(2) Å, b =5.8533(7) Å, c =15.324(2) Å, b =97.271(2)°, V =1288.7 Å 3 , Z =4,Rgt(F) =0.065, wRref (F 2 ) =0.164, T =298 K. Source of materialHydrazine monohydrate (3 ml) in ethanol (10 ml) was added dropwise to arefluxing ethanol (30 ml) solution of the appropriate 1-(furan-2-yl)-3-(naphthalen-6-yl)propane-1,3-dione (2.64 g). The solution was refluxed for 3hand the solvent was removed by evaporation. The residual solid was recrystallized from dillute ethanol solution to give the title compound (yield 1.98 g, 76 %). Crystals suitable for X-ray diffraction were grown by slow evaporation of the CH 2 Cl 2 /EtOH (1:2, v/v)solution at room temperature. Experimental detailsThe O1 and C15 on furan ring were found to be disordered, with the occupancies of the positions O1/O1'and C15/C15' refined to 0.53/0.47. Hatoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C-Hdistances of 0.93 to 0.97 Å,a nd with U iso (H) =1 .2 U eq (C). All H atoms on Natoms were positioned geometrically and refined as riding atoms with d(N-H) =0.86 Å and U iso (H) =1.2 U eq (N). The possible reason of the high Rvalues is the poor quality of selected crystal. DiscussionPyrazoles are an important class of heteroaromatic ring systems that find extensive use in the pharmaceutical industry [1,2]. Pyrazoles crystallize with four hydrogen-bonding patterns -dimers, trimers, tetramers and catemers through N−H···Nhydrogen interactions using both Natoms of the pyrazole [3,4]. In the title crystal structure the molecule adopts aH -bonded catemer structure. Proton of the pyrazole group is resided at the nitrogen atom N1. The entire molecule is approximately planar, the pyrazolyl ring makes dihedral angles of 3.66(4)°and 8.38(4)°w ith two aromatic rings (C1/C4/C9/C10 and O1/C14-C17), respectively. The N2 atom form strong intermolecular hydrogen bonds with the pyrazole proton on atom N1 of the neighboring molecule. This is evidenced by the short N1···N2 distance of 2.999(2) Å,which is comparable to that of the N···Nbonding observed in the related, 3-methyl-5-phenyl-pyrazole and 3,5-diphenylpyrazole, which formed the tetrameric structures in the solid state (2.824(5) -2.913(5) Å) [5]. The distances of N1-H1A and N2···H1A hydrogen bonds are 0.89(3) and 2.11(3) Å,respectively. As shown in bottom figure, molecules are linked into chains via N−H···Nintermolecular hydrogen bonds, the aromatic p-p stacking interactions between the furan ring and the pyrazole ring, Cg1-Cg2 i [centroid-centroid distance of 3.644 (4) Å, symmetry code i: x,−1+y,z,where Cg1 and Cg2 are centroids of the furan ring (O1/C14-C16) and the pyrazole ring (N1/N2/C13-C11), respectively] may further stabilize the structure.

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Excited-State Intramolecular Proton Transfer in Five-Membered Hydrogen-Bonding Systems: 2-Pyridyl Pyrazoles

Cited by 169 publications

References 6 publications

Crystal structure of 3-(furan-2-yl)-5-(4-methoxyphenyl)-1H-pyrazole, C14H12N2O2

Crystal structure of 3-(furan-2-yl)-5-(4-methoxyphenyl)-1H-pyrazole, C14H12N2O2

Crystal structure of 3-(furan-2-yl)-5-(4-phenylphenyl)-1H-pyrazole — methanol (1:1), C19H14N2O · CH3OH

Crystal structure of 3-(furan-2-yl)-5-(naphthalen-6-yl)-1H-pyrazole, C17H12N2O

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