Synthesis and Crystal Structure of a Depside Derivative 2-(2-Methoxy-2-oxoethyl)phenyl 2-(3,4-Dimethoxyphenyl)acetate

Abstract  

A depside derivative, 2-(2-methoxy-2-oxoethyl)phenyl 2-(3,4-dimethoxyphenyl)acetate (3), was synthesized through a facile approach in high yields. Its structure was confirmed by ¹H NMR, ¹³C NMR, ESI mass spectra, elemental analyses and X-ray single crystal diffraction study. Crystal structure analysis revealed that compound 3 crystallized in the monoclinic, space group P2₁/c with the following unit cell parameters: a = 10.173(2) Å, b = 10.459(2) Å, c = 16.516(3) Å, α = 90°, β = 102.30(3)°, γ = 90°, V = 1717.0(6) Å³, Z = 4.     

Hydrogen Bonded 3D Supramolecular Architectures of Two Organic Salts Assembled from 2-Aminoheterocyclic Compounds and Phosphoric Acid

Abstract  

Two phosphate salts (2-aminopyrimidine): (phosphoric acid): H₂O [HL1⁺ (H₂PO₄) ⁻ ]·H₂O (1), and (4-phenylthiazol-2-amine): (phosphoric acid) [HL2⁺·(H₂PO₄)⁻] (2) based on 2-aminoheterocyclic compounds, 2-aminopyrimidine (L1), and 4-phenylthiazol-2-amine (L2) were prepared and structurally characterized by X-ray crystallography. Compound 1 crystallizes in the triclinic, space group P-1, with a = 6.2201(7) Å, b = 8.6139(9) Å, c = 9.4800(10) Å, α = 109.685(2)°, β = 106.3340(10)°, γ = 95.4450(10)°, V = 448.72(8) Å³, Z = 2. For 1, the cations were linked to each other via intermolecular C–H···N hydrogen bonds to form a 1-D chain structure running along the a-axis direction. The anions and the water molecules were connected alternatively along the a-axis direction through O–H···O hydrogen bonds to form a 1-D chain also. The cationic chains and the anionic chains were alternatively connected along the c-axis direction through N–H···O and C–H···O hydrogen bonds to form a 2D corrugated sheet. Adjacent sheets were combined together through π–π interaction to form double sheet. These double sheets were further joined together by O–H···O and N–H···O hydrogen bonds to produce a 3D network structure. Compound 2 crystallizes in the Orthorhombic, space group Pbca, with a = 10.1929(10) Å, b = 8.4406(9) Å, c = 27.589(2) Å, α = 90°, β = 90°, γ = 90°, V = 2373.6(4) Å³, Z = 8. In 2, the phosphates formed 1D chain along the b-axis through two P–O–H···O = P hydrogen bonds. The cations formed 1D zigzag chain along the b-axis direction under the CH–π interaction. The anionic chains were intercalated between two adjacent cationic chains through N–H···O, O–H···O, C–H···O, and O–S contacts. Such stacking repeated along the c-axis direction to form a 3D network structure.     

Structures of Three New (Phenylsulfonyl)Indole Derivatives

Abstract  

Three new 1-(phenylsulfonyl)indole derivatives, 3-acetyl-2-ethyl-1-(phenylsulfonyl)indole, (I), 2-benzyl-1-(phenylsulfonyl)indole, (II), and 3-trimethylsilylethynyl-1-(phenylsulfonyl)indole, (III), have been synthesized and their crystal structures determined by single crystal X-ray crystallography. (I), C₁₈H₁₇NO₃S, is triclinic with space group P-1 and cell constants: a = 8.6129(2) Å, b = 8.8366(2) Å, c = 11.0108(2) Å, α = 72.7920(1)°, β = 75.0120(1)°, γ = 77.2550(1)°, V = 763.79(3) ų and Z = 2. (II), C₂₁H₁₇NO₂S, is monoclinic with space group P21/n and cell constants: a = 10.8355(18) Å, b = 10.6987(19) Å, c = 14.472(3) Å, β = 75.0120(1), V = 1675.2(5) ų and Z = 4. (III), C₁₉H₁₉NO₂SSi, is monoclinic with, space group P21/c and cell constants: a = 12.9596(1) Å, b = 10.543(3) Å, c = 13.543(2) Å, β = 93.58°, V = 1846.8(6)ų and Z = 4. All three have the same (phenylsulfonyl)indole skeleton with different ligands attached to the 2- and 3-sites of the indole ring. The angle between the mean planes of the indole and benzyl groups is 76.9(6)° (I), 82.9(3)° (II), 89.6(2)° (III) and between the sulfonyl group with the indole and benzyl rings is 61.2(9)° (I), 59.0((5)° (II), 51.5(6)°, 42.5(8)° (III) and 51.5(6)°(I), 44.3(8)° (II), 47.2(8)° (III), respectively. In addition to the ligand substitutions, weak intermolecular C–H···O hydrogen bond interactions and π stacking interactions between the π orbitals of nearby indole and phenyl rings influence these twist angles. Comparison to a MOPAC AM1 computational calculation supports these observations.     

Synthesis and Crystal Structure Analysis of Methyl 2-Hydroxyimino-3-phenyl-propionate

Abstract  

As precursors of α-amino acids, methyl 2-hydroxyimino-3-phenyl-propionate (F.W. 193.20) was synthesized, characterized by ¹H NMR, IR, element analysis and confirmed by X-ray crystal structure analysis. This compound crystallizes in monoclinic class under the space group P2₁/c with cell parameters, a = 8.6435(17) Å, b = 5.4957(11) Å, c = 21.146(4) Å; β = 97.12(3)°, and Z = 4. The structure exhibits inter-molecular hydrogen bonds of the type O–H···N, O–H···O, C–H···O.     

Crystal Structure of [Zn(2-Bromobenzoato)<Subscript>2</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> and [Zn(2-Bromobenzoato)<Subscript>2</Subscript>(<Emphasis Type="Italic">N</Emphasis>-Methylnicotinamide)]<Subscript>2</Subscript>

Abstract  

The syntheses and structural characterizations of two novel 2-bromobenzoatozinc(II) complexes—[Zn(2-BrC₆H₄COO)₂] _n (I) and [Zn(2-BrC₆H₄COO)₂(mnad)]₂ (II), where mnad is N-methylnicotinamide are reported. Compound (I) crystallized with a monoclinic lattice (space group P2₁/c) and is polymeric in solid state. Its cell parameters are: a = 7.37220(10) Å, b = 19.9639(3) Å, c = 30.2756(5) Å, β = 94.7510(7)°, V = 4440.59(12) ų, Z = 4. The coordination environments of all zinc atoms are distorted tetrahedra built from four carboxylate oxygen atoms coming from four 2-bromobenzoato ligands. Compound (II) crystallized with a monoclinic lattice (space group P2₁/c) with a = 11.7488(2) Å, b = 20.3683(3) Å, c = 9.30130(10) Å, β = 100.3941(11)°, V = 2189.30(5) ų, Z = 2. This dimeric molecule features a paddle-wheel [Zn₂O₈] cage in solid state; the coordination environment of the central atom is square pyramidal consisting of four carboxylate oxygen atoms and the pyridine N atom of the mnad ligand.     

Crystal Structure of 3-(4-Methoxy-benzylidene)-isothiochroman-4-one

Abstract  

The title compound, 3-(4-methoxy-benzylidene)-isothiochroman-4-one (C₁₇H₁₄O₂S) was prepared from the reaction of isothiochroman-4-one with benzaldehyde in the presence of small amount of HCl. The structure of the synthesised compound was determined by IR, ¹H NMR and X-ray crystallography. The structure was solved in monoclinic, space group P2₁/n with a = 3.9773 (7) Å, b = 10.918 (2) Å, c = 30.609 (6) Å, β = 90.615 (3)°, V = 1329.1 (4) Å³, Z = 4 and with R _int = 0.047. The bicyclic ring of isothiochroman-4-one moiety does not adopt a planar geometry. The molecular conformation is stable via C10–H···O1 and C16–H···S1 intramolecular hydrogen-bonding interactions. These contacts involve molecules in an extended two-dimensional sheet to the bc plane.     

Crystal Structure of 4-Bromo-3,4-Dichloro-1-(1-Morpholinyl)-1-(Decylsulfanyl)-2-Nitro-Buta-1,3-Diene

Abstract  

The compound 4-bromo-3,4-dichloro-1-(1-morpholinyl)-1-(decylsulfanyl)-2-nitro-buta-1,3-diene was synthesized from the reaction of 4-bromo-1,3,4-trichloro-1-(decylsulfanyl)-2-nitro-buta-1,3-diene with morpholine and characterized by elemental analysis, IR spectrum, UV spectra, ¹H NMR,¹³C NMR and X-ray single crystal determination. In the title compound, C₁₈H₂₉BrCl₂N₂O₃S, crystallizes in the monoclinic space group P2₁/c, a = 15.8326(4) Å, b = 8.9915(10) Å, c = 16.7528(5) Å, β = 100.808(10)°, V = 2,342.6(3) Å³, Z = 4, R ₁ = 0.0590 and wR ₂ = 0.0940. The morpholine ring adopts a chair conformation. The morpholine ring and the butadiene group are inclined at an angle of 113.4 (1)°. The butadiene unit is not planar as can be expected if the two double bonds are fully conjugated.     

Synthesis and Structural Characterization of Bis[(cyclohexylamino)pent-2-en-4-onato]-Chromium(II)

Abstract  Addition of one equivalent of CrI₂ to two equivalents of lithium cyclohexylamino-pent-2-en-4-onate results in bis[(cyclohexylamino)pent-2-en-4-onato]-chromium(II). Crystallization in diethylether reaction solvent forms the hemi-etherate A with the asymmetric unit showing two target compounds and one molecule of cocrystallized diethylether in the P-1 space group with crystal cell parameters a = 12.931(4) Å, b = 13.207(4) Å, c = 16.104(5) Å, α = 66.559(5)°, β = 77.670(5)°, γ = 81.562(5)°, V = 2,459.1(14) Å³ and Z = 4. Drying A in vacuo and recrystallization in pentane yields a nonsolvated crystalline phase B with an asymmetric unit displaying only one molecule of the target compound in the P2₁/c space group with crystal cell parameters a = 14.290(7) Å, b = 14.082(7) Å, c = 11.246(6) Å, β = 94.807(8)°, V = 2,255.1(19) Å³ and Z = 4. Graphical Abstract  A Cr(II) complex supported by two β-enaminoketiminato ligands, bis[(cyclohexylamino)pent-2-en-4-onato]-chromium(II), has been synthesized and has been structurally characterized in two different crystal phases.      

Synthesis,Characterization and Crystal Structure Determination of a Hepta-coordinated Cadmium(II) Complex with Thiocyanato-bridges

Abstract  A new cadmium(II) complex [(C₂₈H₂₄N₆)Cd(SCN)₂]₂(CH₃OH)₂ (1) has been synthesized and characterized by IR, UV spectra, TG-DTA technique and single crystal X-ray diffraction analysis. The crystallographic data for compound 1: triclinic P1ˉ, a = 9.630(2) Å, b = 11.123(3) Å, c = 15.396(4) Å, α = 106.93(1)°, β = 91.60(1)°, γ = 99.99(1)°, V = 1,548.5(6) Å³, Z = 1, Dc = 1.512 mg/m³, F(000) = 716, R ₁ = 0.0332, wR ₂ = 0.0907. The molecule contains a symmetrical dinuclear unit in which two Cd(II) ions are double bridged by two di-μ-1,3-SCN⁻ anoins with a cadmium–cadmium separation of 6.48 Å. Each Cd(II) ion is seven-coordinated with six nitrogen atoms and a sulfur atom to form a monocapped trigonal prism coordination geometry. In addition, the molecule is further connected by multiform intermolecular C–H···π, π···π interactions and hydrogen bonds to form a three-dimensional supramolecular structure. Graphical Abstract  A hepta-coordinated Cd(II) complex which exhibits a distorted a monocapped trigonal prism coordination geometry has been achieved by using bisbidentate Schiff-base ligand and thiocyanate anion.      

Synthesis and Crystal Structure of 3-Methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole

Abstract  

The title compound, 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole was synthesized by reaction of diphenylphosphazoanilide with N-acetyl-N′-(2-pyridoyl)hydrazine. Crystals suitable for X-ray analysis were obtained from a mixed solution of water and ethanol in a one-to-one volume ratio. The crystal is orthorhombic, space group P2₁2₁2₁ with crystallographic parameters: a = 19.414(4) Å, b = 17.172(3) Å, c = 7.4850(15) Å, β = 90.00°, μ = 0.079 mm⁻¹, V = 2495.3(8) Å³, Z = 8, Dc = 1.258 g/cm³, F(000) = 992, T = 295(2) K. The X-ray results showed that in the crystal structure of the title compound, the 1,2,4-triazole, pyridine and benzene rings are not coplanar.     

Synthesis, Spectroscopic Characterization and Crystal Structure of a New Acetyl phosphorylamidate P(O)[NHC(O)C6H4(4-NO2)][N(CH(CH3)2)(CH2C6H5)]2

Abstract  

A new acetyl phosphorylamidate P(O)[NHC(O)C₆H₄(4-NO₂)][N(CH(CH₃)₂)(CH₂C₆H₅)]₂ has been synthesized and characterized by elemental analysis, ¹H, ¹³C and ³¹P NMR, IR and single crystal X-ray diffraction. Single crystal X-ray analysis shows that it belongs to triclinic system, space group P[`1] P\bar{1} , with a = 10.5868(16) Å, b = 11.8058(18) Å, c = 12.4364(19) Å, α = 65.410(3)°, β = 67.492(4)°, γ = 85.879(3)°, V = 1,298.6(3) Å³, and Z = 2. The intermolecular PO···HN hydrogen bond makes H-bonded dimer of molecule with Ci symmetry. In the crystal network, the dimers are aggregated in the chain arrays through π-stacking between p-NO₂–C₆H₄–C(O)–NH– moieties. Moreover, weak C–H···O and C–H···π interactions exist in the crystal network.     

Synthesis and Crystallographic Characterization of 1-((2-(2,4-Difluorophenyl)oxiran-2-yl)methyl)-1<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazole: A Crucial Intermediate for the Synthesis of Azole Antifungal Drugs

Abstract  

Preparation of oxirane 3 was accomplished in two steps. 1H-1,2,4-triazole was reacted with 2,4-difluoro-α-chloroacetophenone 1 in presence of K₂CO₃ in refluxing toluene to provide compound 2. Compound 2 was treated with trimethylsulfoxonium iodide (TMSI) in aq. NaOH and toluene to provide oxirane 3. Oxirane 3, previously isolated as an oil, was crystallized from (DCM/MeOH) and characterized by X-ray crystallography: triclinic, space group P − 1, a = 7.3225 (15), b = 7.5833 (15), c = 9.856 (2) Å, α = 91.908 (12), β = 100.824 (11), γ = 103.800 (11)°, V = 520.28 (18) ų, Z = 2. The molecule has a stepped conformation with nearly parallel triazole and phenyl rings. Lack of classical hydrogen-bond donors leads to packing dominated by weaker interactions, including C–H···N, C–H···F and F···F contacts.     

Synthesis,Crystal Structures and Magnetic Properties of Two Three-Dimensional Cerium(III) and Erbium(III) Coordination Polymers

Abstract  

Two lanthanide(III) coordination polymers, namely [Ce(pzdc)_1.5(H₂O)] _n (1), [Er(pzdc)(μ₂-OH)(H₂O)] _n ·nH₂O (2) (H₂pzdc = pyrazine-2,5-dicarboxylic acid), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction and magnetic measurements. Polymer 1 crystallizes in triclinic space group P-1, with a = 6.2875(6), b = 6.7396(6), c = 13.3858(14) Å, α = 82.858(4), β = 83.118(4), γ = 63.452(4)°, V = 502.16(8) Å³, and Z = 2. Polymer 2 crystallizes in monoclinic space group P2(1)/c, with a = 11.706(4), b = 6.151(2), c = 14.063(5) Å, β = 92.255(3), V = 502.16(8) Å³, and Z = 4. Single-crystal X-ray diffraction studies show that compound 1 possess a 3D framework structure consisted of double chains. Compound 2 features a 3D open framework structure with a dinuclear Er(III) secondary building unit. Magnetic studies for complex 1 show stronger antiferromagnetic coupling between the Ce(III) ions.     

Co-crystal Structure of 11-Hydroxy-2,3,9-trimethoxy-6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">b</Emphasis>]chromen-12-one and 11-Hydroxy-2,3,9-trimethoxy-chromeno[3,4-<Emphasis Type="Italic">b</Emphasis>]chromene-6,12-dione

Abstract  

A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) was crystallized from the reaction mixture of 6-deoxyclitoriacetal and methanesulfonyl chloride, and its structure was characterized by X-ray diffraction. This co-crystal crystallizes in a triclinic crystal system, space group P(−1) with unit cell parameters of a = 8.1317(3) Å, b = 9.8224(4) Å, c = 10.7268(3) Å, α = 78.116(1)°, β = 77.463(1)°, γ = 77.140(1)°, Z = 2 and V = 804.11(3) Å³. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F ² to final values of R ₁ = 0.0501 and wR ₂ = 0.1520.     

Synthesis,Crystal Structure and Hydrogen-Bonding Patterns in (RS)-1-Carbamoyl Pyrrolidine-2-Carboxylic Acid

Abstract  

The title compound, N-carbamoyl-dl-proline, C₆H₁₀N₂O₃, crystallizes in the triclinic P-1 space group with unit cell parameters a = 7.610 (4) Å, b = 9.259 (5) Å, c = 11.749 (7) Å, α = 110.294 (11)°, β = 101.304 (13)°, γ = 91.391 (16)°, with two crystallographically independent molecules in the asymmetric unit. The ureido and carboxyl groups are equatorial and axial to the pyrrolidine rings, respectively. The pyrrolidine rings adopt envelope and twisted conformations in the residue A and B, respectively. The molecules are joined by N–H···O and O–H···O hydrogen bonds into cyclic structures with graph set R ₂²(8), forming infinite chains parallel to the cb plane with graph set C ₂²(14), that are further connected via N–H···O hydrogen bonds into a three-dimensional network.     

Synthesis,Crystal Structure and Optical Properties of a Three-Dimensional Supramolecule Assembled by a Dinuclear Neodymium Cluster

Abstract  

The reaction of isonicotinic acid (IN), sodium hydroxide, 1,10-phenanthroline (phen) and neodymium nitrate leads to the formation of a novel complex [Nd(phen)(IN)₂(NO₃)(H₂O)₂]₂ 1, which has been characterized by single crystal X-ray diffraction analysis: monoclinic, space group C2/c, with a = 24.93(2) Å, b = 9.452(3) Å, c = 21.406(5) Å, β = 97.87(2)°, and Z = 4. Complex 1 consists of a centrosymmetric dinclear molecule, and neodymium atoms are bridged by two carboxyl groups of two IN ligands. The dinuclear clusters of 1 are connected each other into a three-dimensional (3D) supramolecular framework, which is stabilized by O–H···O, O–H···N hydrogen bonds as well as π–π stacking interactions. Its electronic absorption and luminescence properties have also been investigated.     

Synthesis,Crystal Structures and Physicochemical Properties of Poly[bis(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylformamide)tetra(thiocyanato)metal(II) Mercury(II)] (Metal = Cadmium and Manganese)

Abstract  

Two novel single crystals, poly[bis(N,N-dimethylformamide)tetra(thiocyanato)metal(II)mercury(II)] (metal = cadmium and manganese, abbreviated as DTCM and DTMM, respectively) were prepared. The characterizations of DTCM and DTMM were performed by elemental analyses, infrared, X-ray single crystal diffraction. The two title complexes crystallized in the same monoclinic crystallographic system and P2₁/n space group with unit cell parameters: a = 9.2515(2) Å, b = 14.1670(3) Å, c = 16.5898(3) Å, β = 93.0320(10)°, z = 4, D _x  = 2.115 g/cm³ for DTCM, and a = 9.24580(10) Å, b = 14.1110(2) Å, c = 16.4937(2) Å, β = 92.9120(10)°, z = 4, D _x  = 1.960 g/cm³ for DTMM, respectively. The two structures are isostructural. The thermal decomposition processes of the two crystals were investigated by means of thermogravimetric analysis and differential thermal analysis measurements in air.     

Absolute Configuration of Two Eudesmane Derivatives from <Emphasis Type="Italic">Verbesina turbacensis</Emphasis> H.B.K.

Abstract  

Two compounds isolated from the aerial parts of Verbesina turbacensis H.B.K, are reported in this work. Both compounds crystallize in the orthorhombic system, space group P2₁2₁2₁. Compound (1), 6β-[cinnamoyloxy]-3β,4α-dihydroxyeudesmane, formula C₂₄H₃₄O_4, has unit cell parameters a = 9.6234(2), b = 12.3137(3) and c = 18.6277(5) Å, V = 2207.38(9) Å³, Z = 4. On the other hand, 6β-[cinnamoyloxy]-eudesman-15-oic acid (2), formula C₂₄H₃₂O_4, has cell parameters a = 8.7035(3), b = 14.2020(4), c = 17.1590(5) Å, V = 2120.97(11) Å³, Z = 4.     

Synthesis,Crystal Structure and Characterizations of New 3,4,7,8-Tetrachloro-1,10-Phenanthroline Zn(II) Complex

Abstract  

A novel 3,4,7,8-tetrachloro-1,10-phenanthroline (Cl₄phen) Zn(II) complex has been synthesized. The complex, [Zn(Cl₄phen)₂(H₂O)₂](NO₃)₂·CH₃CH₂OH (1), has been identified and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR, thermogravimetric analysis and photoluminescence studies. Single crystal X-ray diffraction analysis reveals that complex (1) belongs to the monoclinic system, space group P2(1)/c, a = 10.061(2) Å, b = 18.924(4) Å, c = 18.189(4) Å, β = 100.94(3)°, and Z = 4. Complex (1) consists of cationic species [Zn(Cl₄phen)₂(H₂O)₂]²⁺, NO₃ ⁻ and CH₃CH₂OH. The zinc atom displays a distorted cis-N₄O₂ octahedral geometry. Via extended Zn–O–H···O–N–O···H–O–Zn bridge, every mononuclear unit is linked with other ones to form one-dimensional (1D) infinite chain of hydrogen bond system. Three-dimensional (3D) polymeric network arrangement was built via weak C–H···O and π-stacking interactions between Cl₄phen moieties. A solvent-dependency effect of complex (1) was observed in spectroscopic properties.     

Ethynyl and Propynylpyrene Inhibitors of Cytochrome P450

Abstract  

The single-crystal X-ray structures and in vivo activities of three aryl acetylenic inhibitors of cytochromes P450 1A1, 1A2, 2A6, and 2B1 have been determined and are reported herein. These are 1-ethynylpyrene, 1-propynylpyrene, and 4-propynylpyrene. To investigate electronic influences on the mechanism of enzyme inhibition, the experimental electron density distribution of 1-ethynylpyrene has been determined using low-temperature X-ray diffraction measurements, and the resulting net atomic charges compared with various theoretical calculations. A total of 82,390 reflections were measured with Mo Kα radiation to a (sinθ/λ)_max = 0.985 Å⁻¹. Averaging symmetry equivalent reflections yielded 8,889 unique reflections. A least squares refinement procedure was used in which multipole parameters were added to describe the distortions of the atomic electron distributions from spherical symmetry. A map of the model electron density distribution of 1-ethynylpyrene was obtained. Net atomic charges calculated from refined monopole population parameters yielded charges that showed that the terminal acetylenic carbon atom (C18) is more negative than the internal carbon (C17). Net atomic charges calculated by ab initio, density functional theory, and semi-empirical methods are consistent with this trend suggesting that the terminal acetylenic carbon atom is more likely to be the site of oxidation. This is consistent with the inhibition mechanism pathway that results in the formation of a reactive ketene intermediate. This is also consistent with assay results that determined that 1-ethynylpyrene acts as a mechanism-based inhibitor of P450s 1A1 and 1A2 and as a reversible inhibitor of P450 2B1. Crystallographic data: 1-ethynylpyrene, C₁₈H₁₀, P2₁/c, a = 14.571(2) Å, b = 3.9094(5) Å, c = 20.242(3) Å, β = 105.042(2)°, V = 1,113.5(2) Å³; 1-propynylpyrene, C₁₉H₁₂, P2₁/n, a = 8.970(2) Å, b = 10.136(1) Å, c = 14.080(3) Å, β = 99.77(2)°, V = 1,261.5(4) Å³; 4-propynylpyrene, C₁₉H₁₂, Pbca, a = 9.904(1) Å, b = 13.174(2) Å, c = 19.401(1) Å, V = 2,531.4(5) Å³.