9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetra-methyl-4,5,6,9-tetra-hydro-3H-xanthene-1,8(2H,7H)-dione.
01 Aug 2011-Acta Crystallographica Section E-structure Reports Online (International Union of Crystallography)-Vol. 67, Iss: 8
TL;DR: In the title compound, C23H26O4, the two cyclohexene rings adopt envelope conformations whereas the pyran ring adopts a boat conformation.
Abstract: In the title compound, C23H26O4, the two cyclohexene rings adopt envelope conformations whereas the pyran ring adopts a boat conformation. In the crystal, pairs of intermolecular O—H⋯O hydrogen bonds link the molecules into inversion dimers.
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TL;DR: The results show that all the derivatives of xanthenedione molecules adopt the same structural conformation, where the central ring has a shallow boat conformation and the outer rings have a twisted boat conformed.
Abstract: The existence of intermolecular interactions and the conformational geometry adopted by molecules are related to biological activity. Xanthenedione molecules are promising and emerging antioxidants and acetylcholinesterase inhibitors. To examine the role of different functional groups involved in the intermolecular interactions and conformational geometries adopted in xanthenediones, a series of three substituted xanthenediones have been crystallized [9-(3-hydroxyphenyl)-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione, C23H26O4, 9-(5-bromo-2-methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-2H-xanthene-1,8(5H,9H)-dione, C24H27BrO4, and 3,3,6,6-tetramethyl-9-(pyridin-2-yl)-3,4,6,7-tetrahydro-2H-xanthene-1,8(5H,9H)-dione, C22H25NO3] and their intermolecular interactions analyzed via Hirshfeld analysis. The results show that all the derivatives adopt the same structural conformation, where the central ring has a shallow boat conformation and the outer rings have a twisted boat conformation. The intermolecular interactions in the molecules are predominantly O-H...O, C-H...O and π-π interactions. The optimized structures of the derivatives from theoretical B3LYP/6-311G** calculations show a good correlation with the experimental structures. The lattice energy involved in the intermolecular interactions has been explored using PIXELC.
4 citations
Cites background from "9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..."
...Out of these, 3 hits are similar to C1, but the hydroxy group(s) are at different positions, with or without a methoxy group, and the hit (AWUGUV; Fun et al., 2011), which has only one –...
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...The bond lengths and angles are within normal ranges [CSD refcodes YAVTIOS (Sughanya & Sureshbabu, 2012), AWUGUV (Fun et al., 2011) and QUYGUN (Noorhafizah Hasanudin et al., 2010)]....
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TL;DR: In the title compound, C22H22O4, the two cyclohexenone rings adopt half-chair conformations, whereas the six-membered pyran ring adopts a flattened boat conformation.
Abstract: In the title compound, C22H22O4, the two cyclohexenone rings adopt half-chair conformations, whereas the six-membered pyran ring adopts a flattened boat conformation, with the O and methine C atoms deviating from the plane of the other four atoms by 0142 (2) and 0287 (2)A, respectively In the crystal, weak C—H⋯O hydrogen bonds link molecules into chains running parallel to the a axis
1 citations
Cites background from "9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..."
...1), the bond lengths and angles are normal and correspond to those observed in related struc- tures (Asad et al., 2012; Fun et al., 2011; Mehdi et al., 2011)....
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1 citations
TL;DR: In the title compound, C21H19ClO3, the two cyclohexenone rings adopt half-chair conformations, whereas the pyran ring adopts a boat conformation.
Abstract: In the title compound, C21H19ClO3, the two cyclohexenone rings adopt half-chair conformations, whereas the pyran ring adopts a boat conformation The 4-chlorophenyl ring is almost perpendicular to the plane through the four C atoms of the pyran ring [dihedral angle = 8797 (6)°] In the crystal, weak C—H⋯O hydrogen bonds link the molecules into a chain parallel to the a-axis
Cites background from "9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..."
...The bond lengths and angles are normal and correspond to those observed in related structures (Asad et al., 2012; Fun et al., 2011; Mehdi et al., 2011)....
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TL;DR: In the case of C24H27BrO5, the mean plane and maximum deviations of the central pyran ring are 0.0384 and 0.0733, respectively.
Abstract: In the fused ring system of the title compound, C24H27BrO5, the mean plane and maximum deviations of the central pyran ring are 0.0384 (2) and 0.0733 (2) A, respectively. The cyclohexenone rings both adopt envelope conformations with the tetra-substituted C atoms as flap atoms, whereas the central pyran ring adopts a flattened boat conformation. The central pyran and phenyl substituent rings are almost perpendicular to each other, making a dihedral angle of 89.71 (2)°. In the crystal, pairs of molecules are linked via O—H⋯O hydrogen bonds, forming inversion dimers with an R22(20) ring motif. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (50.6%), O⋯H/H⋯O (22.9%) and C⋯H/H⋯C (11.1%) contacts. Quantum chemical calculations for the frontier molecular orbitals were undertaken to determine the chemical reactivity of the title compound.
References
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TL;DR: This paper could serve as a general literature citation when one or more of the open-source SH ELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.
Abstract: An account is given of the development of the SHELX system of computer programs from SHELX-76 to the present day. In addition to identifying useful innovations that have come into general use through their implementation in SHELX, a critical analysis is presented of the less-successful features, missed opportunities and desirable improvements for future releases of the software. An attempt is made to understand how a program originally designed for photographic intensity data, punched cards and computers over 10000 times slower than an average modern personal computer has managed to survive for so long. SHELXL is the most widely used program for small-molecule refinement and SHELXS and SHELXD are often employed for structure solution despite the availability of objectively superior programs. SHELXL also finds a niche for the refinement of macromolecules against high-resolution or twinned data; SHELXPRO acts as an interface for macromolecular applications. SHELXC, SHELXD and SHELXE are proving useful for the experimental phasing of macromolecules, especially because they are fast and robust and so are often employed in pipelines for high-throughput phasing. This paper could serve as a general literature citation when one or more of the open-source SHELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.
81,116 citations
"9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..." refers methods in this paper
...Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009)....
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...Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL…...
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TL;DR: In this article, a unique mean plane is defined for a general monocyclic puckered ring, which is described by amplitude and phase coordinates which are generalizations of those introduced for cyclopentane by Kilpatrick, Pitzer, and Spitzer.
Abstract: A unique mean plane is defined for a general monocyclic puckered ring. The geometry of the puckering relative to this plane is described by amplitude and phase coordinates which are generalizations of those introduced for cyclopentane by Kilpatrick, Pitzer, and Spitzer. Unlike earlier treatments based on torsion angles, no mathematical approximations are involved. A short treatment of the four-, five-, and six-membered ring demonstrates the usefulness of this concept. Finally, an example is given of the analysis of crystallographic structural data in terms of these coordinates. Although the nonplanar character of closed rings in many cyclic compounds has been widely recognized for many years, there remain some difficulties in its quantitative specification. An important first step was taken by Kilpatrick, Pitzer, and Spitzer in their 1947 discussion of the molecular structure of cyclopentane.' Starting with the normal modes of out-of-plane motions of a planar regular pentagon,* they pointed out that displacement of the j t h carbon atom perpendicular to the plane could be written 2 112 zj = (/'SI 4 COS (2+ + 4 n ( j 11/51 (11 where q is a puckering amplitude and $ is a phase angle describing various kinds of puckering. By considering changes in an empirical potential energy for displacements perpendicular to the original planar form, they gave reasons to believe that the lowest energy was obtained for a nonzero value of q (finite puckering) but that this minimum was largely independent of $. Motion involving a change in fi at constant q was described as pseudorotation. Subsequent refinement of this work has involved models in which constraints to require constant bond lengths are imposed3q4 and extensions to larger rings5-' and some heterocyclic systems are considered.* Although the correctness of the model of Kilpatrick, et a f . , I and the utility of the (q. $) coordinate system is generally accepted, application to a general five-membered ring with unequal bond lengths and angles is not straightforward. Given the Cartesian coordinates for the five atoms (as from a crystal structure), determination of puckering displacements z, requires specification of the plane z = 0. A least-squares choice (minimization of Zz i2) is one possibility, but the five displacements relative to this plane cannot generally be expressed in terms of two parameters q and $ according to eq 1. An attempt to define a generalized set of puckering cordinates which avoids these difficulties was made by Geise, Altona, Romers, and S~ndara l ingam.~l ' Their quantitative description of puckering in five-membered rings involves the five torsion angles 0, rather than displacements perpendicular to some plane. These torsion angles are directly derivable from the atomic coordinates and are all zero in the planar form. They proposed a relationship of the form\
6,526 citations
"9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..." refers background in this paper
...For ring conformations, see: Cremer & Pople (1975)....
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...The cyclohexene rings (C1–C6 & C8–C13) adopt envelope conformations [φ = 118.78 (11)° and Θ = 58.70 (9)°; φ = 3.56 (12)° and Θ = 120.92 (10)°] whereas the pyran ring adopts a boat conformation [φ = 355.6 (5)° and 114.4 (4)°; Cremer & Pople, 1975)....
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TL;DR: In this paper, a continuous nitrogen-flow cooling device for X-ray diffraction studies is described, which works in the range 77.4 to 323.0 k with a precision of ± 0.1 k and a liquid-nitrogen constant consumption rate of 0.5 k−1 over the whole temperature range.
Abstract: A continuous nitrogen-flow cooling device, generally applicable to X-ray diffraction studies, is described. The device works in the range 77.4 to 323.0 K with a precision of ±0.1 K and a liquid-nitrogen constant consumption rate of 0.5 l h−1 over the whole temperature range. The supply vessel is unpressurized, so that refilling can be done without any observable influence on the cooling of the sample.
1,946 citations
"9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..." refers methods in this paper
...The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. Geometry....
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...For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986)....
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TL;DR: Three lipophilic pH indicators made by covalently binding the xanthene dyes fluoresce in, eosin or dichlorofluorescein to the amino group of phosphatidylethanolamine were incorporated into phospholipid vesicles and the effect of pH on the fluorescence was characterized and it was concluded that these probes were promising candidates for the measurement of pH values at cell surfaces.
Abstract: We have been developing the use of plasma-membrane-bound fluorescent probes to measure the pH values at the surfaces of living chondrocytes. For this purpose, three lipophilic pH indicators were made by covalently binding the xanthene dyes fluorescein, eosin or dichlorofluorescein to the amino group of phosphatidylethanolamine. The probes were incorporated into phospholipid vesicles and the effect of pH on the fluorescence was characterized. Fluorescence was measured at a single emission wavelength during excitation at two wavelengths, and the ratio of the intensities was calculated. The experimentally observed pKobs. values were determined by fitting the fluorescence ratios to the Henderson-Hasselbalch equation. All three probes acted as pH indicators, and the eosinyl-, dichlorofluoresceinyl- and fluoresceinylphosphatidylethanolamines had pKobs. values of 3.5, 6.3 and 7.5 respectively. At physiological salt concentrations, changes in the composition of the vesicle membrane had little effect on these values. We concluded that these probes were promising candidates for the measurement of pH values at cell surfaces.
375 citations
Additional excerpts
...…and their microbial activity, see: Jonathan et al. (1988); Hatakeyama et al. (1988); Shchekotikhin & Nikolaeva (2006); Hilderbrand & Weissleder (2007); Pohlers & Scaiano (1997); Knight & Stephens (1989); Reddy et al. (2010); Rathore et al. (2009); Rajesh et al. (2010); Mookiah et al. (2009)....
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TL;DR: This protocol provides access to water-soluble dyes with large Stoke's shifts and far-red fluorescence emission that are envisioned as components of fluorescence-based sensors for a variety of imaging applications.
86 citations
"9-(4-Hy-droxy-phen-yl)-3,3,6,6-tetr..." refers background in this paper
...…to xanthene derivatives and their microbial activity, see: Jonathan et al. (1988); Hatakeyama et al. (1988); Shchekotikhin & Nikolaeva (2006); Hilderbrand & Weissleder (2007); Pohlers & Scaiano (1997); Knight & Stephens (1989); Reddy et al. (2010); Rathore et al. (2009); Rajesh et al.…...
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