This chapter contains sections titled: Introduction The Crystal Structure of Ethyl Chlorophyllide a·2H2O Visible Spectroscopy of the Chlorophylls A Structural Model for Chlorophyll a Aggregates in vitro Structural Models for Chlorphyll Aggregates in vivo Summary

The (1)H NMR spectra of 10-benzyl-9,11-diphenyl-10-azatetracyclo[6.3.0.0.(4,11)0.(5,9)]undecane (BnPh(2)()) and 10-methyl-9,11-diphenyl-10-azatetracyclo[6.3.0.0.(4,11)0.(5,9)]undecane (MePh(2)()) decoalesce due to slowing inversion at nitrogen and to slowing isolated bridgehead phenyl rotation. The high nitrogen inversion barriers in MePh(2)() (DeltaG() = 12.2 +/- 0.1 kcal/mol at 250 K) and BnPh(2)() (DeltaG() = 10.6 +/- 0.1 kcal/mol at 215 K) are typical of tertiary amines in which at least one C-N-C bond angle is constrained to a small value. Compared to the minuscule rotation barriers about sp(2)-sp(3) carbon-carbon bonds in simple molecular systems, the bridgehead phenyl rotation barriers in MePh(2)() (DeltaG() = 9.8 +/- 0.1 kcal/mol at 210 K) and BnPh(2)() (DeltaG() = 9.8 +/- 0.1 kcal/mol at 210 K) are unusually high. Molecular mechanics calculations (MMX force field) suggest that the origin of the high phenyl rotation barriers lies in the close passage of an o-phenyl proton and a methyl (or benzylmethylene) proton in the transition state. BnPh(2)() crystallized from hexane as white needles in the monoclinic system Pn. Unit cell dimensions are as follows: a = 12.198(1) Å, b = 6.1399(6) Å, c = 14.938(2) Å, beta = 107.470(4) degrees, V = 1067.1(2) Å(3), Z = 2. In the crystal molecular structure, the imine bridge CNC bond angle in BnPh(2)() is constrained to a small value (96 degrees ). The benzylic phenyl group is oriented gauche to the nitrogen lone pair.

We canied out dynamic analysis of humidity-induced phase transitions in nucleoside and nucleotide crystals, e.g.guanosine and disodium adenosine 5'triphosphate(Na2ATP), by the X-ray diffraction method and low-frequency Raman spcctra.l-3.There exist flexible or switchable interactions which would be called as dynamic interactions.In the crystal exhibiting the phase transition, base moieties of nucleosides and nucleotides are stacked to form a columnar structure.There is a water region between the molecular columns.The number of crystal water molecules in this region is a function of humidity, and the reversible crystal transition proceeds.Intermolecular interactions are classified into two types.The first type is a dynamic interaction.Intercolumnar hydrogenbonding networks vary together with increase or decrease of water molecules.It is noteworthy that 1ibose puckering modes contribute to the reconstruction of hydrogen-bonding networks.The second type is, of course, a static or 1igid interaction which plays a role in holding the crystal lattice.It is well-known that transformation of hydrogen-bonding networks induces stmctural changes of nucleic acids and proteins.Intermolecular interactions ofbiomolecules should be characteiized by coexistence of both types of interactions.

Abstract Two crystalline compounds based on the Zn-tetra (4-carboxyphenyl)porphyrin building block have been prepared and structurally analysed by x-ray diffraction in order to ellucidate the characteristic supramolecular aggregation modes of this functionalized metalloporphyrin moiety. Crystals of the 1:1 complex with sec-phenethyl alcohol (1) are monoclinic, space group I2/a (No. 15), a = 14.420(1), b = 24.678(2), c = 33.688(2) A, β = 90.03(2)°, Dc = 1.082 g/cm3, Z = 8, R = 0.080 for 3053 data. Those of the 1:3 complex with dimethylsulphoxide (2) are monoclinic, space group P21/n (No. 14), a = 14.881(1), b = 8.986(2), c = 37.550(3) A, β = 94.21(1)°, Dc = 1.444 g/cm3, Z = 4, R = 0.093 for 4200 data. The two compounds consist of nearly square-pyramidal five-coordinate metalloporphyrin species, molecules of the sec-phenethyl alcohol (in 1) and dimethylsulphoxide (in 2) linking to the metal center at the axial site. In 2, two additional molecules of dimethylsulphoxide associate through H-bonds to the termin...

The electrochemical synthesis of kappa-(BEDT-TSF)(2)Cu[N(CN)(2)]Br, which is virtually isostructural (Pnma) with the 12.5 K ambient pressure superconductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, has been systematically investigated. The electrical resistivity of kappa-(BEDT-TSF)(2)Cu[N(CN)(2)]Br was measured in the a [rho(300) = 2(1) x 10(-2) Omega cm] and b [rho(300) = 1.7(0.7) x 10(1) Omega cm] crystallographic directions. The resistivity decreased monotonically from 300 to 4 K following a T-2 relationship, but a superconducting state was never achieved. Tight-binding band calculations showed that the Fermi surface of kappa-(BEDT-TSF)(2)Cu[N(CN)(2)]Br is indistinguishable from the BEDT-TTF analogue. STM images were obtained of both the radical cation and the polymeric anion layers. The images were in agreement with partial electron density plots. A 20 K X-ray structure of K-(BEDT-TSF)(2)Cu[N(CN)(2)]Br was obtained and is discussed in detail. One of the BEDT-TSF ethylenedithio groups was still disordered at 20 K; this may have been responsible for the failure to observe superconductivity. Isotropic pressures up to 5 kbar did not induce superconductivity.

Aggregation patterns of tetra(4-pyridyl)porphyrin and of its zinc(II) complex in seven new solid materials have been investigated by X-ray diffraction. The metalloporphyrin compound forms two types of coordination polymers through ligation of the porphyrin periphery on one molecule to the metal center of an adjacent porphyrin. These include one-dimensional chains with a zigzag conformation, as well as three-dimensional, extensively interlinked, polymeric structures. The non-metallated compound reveals a characteristic layered arrangement and interporphyrin stacking of the type which is commonly observed in the structures of tetraphenylporphyrin derivatives. In the absence of a metal center, the basic functionality of the pyridyl substituents is utilized for effective H-bond directed coordination and co-crystallization with solvent/guest components. The stoichiometry of the porphyrin solvation, and the consequent interporphyrin organization in the solid phase, are quite sensitive to the nature of the coordinating solvent.

A series of new ''inclusion'' materials based on tetra-4-methoxyphenyl, tetra-4-hydroxyphenyl and tetra-4-chlorophenyl derivatives of the metalloporphyrin system, in combination with a wide variety of guest molecules and ligands, have been prepared, and their structural systematics analysed. Crystallographic investigations have confirmed that the supramolecular arrangement of the hydroxyphenylporphyrin species is dominated by interporphyrin directional hydrogen-bonding interactions, and consists of continuous networks of strongly coordinated entities with varying degrees of cross-linking and rigidity. Guest molecules can be absorbed in these solids in distinctly defined sites of the lattice: in the small interhost cages of fixed size between adjacent intercoordinated porphyrin hosts, or in extended one-dimensional channels formed between the hydrogen bonded host arrays running parallel or perpendicular to the porphyrin plane. For polar ligands with strong nucleophiles, their potential coordination to the metal center provides an additional recognition factor. The stacking mode (offset geometry or overlapping) of the host metalloporphyrin arrays is also affected by the nature of the incorporated guest/ligand. Materials based on the chloro-substituted porphyrins were found to form similarly networked structural modes, influenced by the molecular shape as well as by halogen-halogen noncovalent interactions. Formation of a polar tubular intermolecular architecture capable of aligning organic dipolar guest molecule in the crystal bulk has also been demonstrated. The methoxy-substituted materials form clathrate-type structures characterized by dense layered arrangement of the porphyrin building blocks in two-dimensions. The various structural features directing the observed modes of the supramolecular architecture, and affecting the host structure as well as the guest mobility in it, are discussed.

Analysis of the molecular packing in over 200 tetraarylporphyrin-based lattice clathrates reveals a strong conservation of host structure. In most cases, formation of porphyrin-based clathrates can be viewed as arising from intercalation of guest molecules into pure host materials. Several modes of intercalation are detected, and characteristic of intercalate structures, staging is observed. Intercalate formation accounts for the relative insensitivity of the host structure to the nature and size of the guest species. The structural conservation observed in this large class of materials facilitates rational modification of the host lattice. Crystallographic data are provided for 75 new porphyrin-based clathrates.

Transition Metal Silyl Complexes, 44. — Preparation of the Binuclear Silyl Complexes (CO)3(R3Si)Fe(μ‐PR′R′′)Pt(PPh3)2 by Oxidative Addition of (CO)3(R′R′′HP)Fe(H)SiR3 to (C2H4)Pt(PPh3)2The complexes (CO)3(R′R′′HP)Fe(H)SiR3 (1) [PHR′R′′ = PHPh2, PH2Ph, PH2Cy; SiR3 = SiPh3, SiPh2Me, SiPhMe2, Si(OMe)3] react with Pt(C2H4)(PPh3)2 to give the dinuclear, silyl‐substituted complexes (CO)3(R3Si)Fe(μ‐PR′R′′)Pt(PPh3)2 (2) in high yields. Upon reaction of 2 (R = R′ R′′ = Ph) with CO, the PPh3 ligand at Pt being trans to the PPh2 bridge is exchanged, and (CO)3(Ph3Si)Fe(μ‐PPh2)Pt(PPh3)CO (3) is formed. Complex 3 is characterized by an X‐ray structure analysis. The rather short Fe — Si distance [233.9(2) pm] and the infrared spectrum of 3 indicate that the Fe — Pt bond is quite polar.

Abstract Structural systematics, programmability, and guest transport are discussed for a large class of lattice clathrates based on tetraarylporphyrins. Key Words: lattice clathratePorphyrinIntercalatemolecular packing

X-ray structural characterization has played a key role in revealing the potential of metalloporphyrin complexes as lattice clathrates, and further structural work is essential to the development of many applications of these ''porphyrin sponges''. Clathrates based on five-coordinate tetraphenylporphyrin (TPP) complexes, however, often exhibit an incomplete inversion disorder that precludes accurate structure determination by standard methods. This report describes a refinement procedure that models the inversion disorder and twinning and allows the extraction of accurate structural information. Multiple-temperature structural data are provided for Fe(III)TPP(benzenethiolate) as the toluene and chlorobenzene solvates, as well as for Fe(III)TPP(p-bromobenzenethiolate) as the toluene solvate. Structural data are also provided for an unsolvated and completely ordered form of Fe(III)TPP(benzenethiolate). Observation of some highly disordered but untwinned specimens of the solvates suggests that the residual order is created at the crystal/solution interface during crystal growth. Structural variations among the ten determinations carried out are consistent with admixed S = 3/2:S = 5/2 ground states for these materials.

Analysis of the crystal structures of over 100 tetraarylporphyrin-based lattice clathrates reveals the extent to which van der Waals interactions between host molecules govern the crystal packing. In all these materials, corrugated sheets of tightly packed porphyrin molecules stack to form arrays of parallel channels in which a remarkable variety of guest species are accommodated. Conservation of the host structure in the absence of any covalent or hydrogen-bonding connection between host molecules suggests an engineering strategy for the designed construction of molecular solids. This strategy is based on the use of rigid molecular building blocks with self-complementary shapes. Identification of the features of the molecular structure responsible for the versatility of tetraarylporphyrin-based clathrates lays the groundwork for the development of new microporous materials. X-ray structural data are provided for 34 new materials.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTetraarylporphyrin sponges. Composition, structural systematics, and applications of a large class of programmable lattice clathratesMarianne P. Byrn, Carol J. Curtis, Saeed I. Khan, Philip A. Sawin, Ryuichi Tsurumi, and Charles E. StrouseCite this: J. Am. Chem. Soc. 1990, 112, 5, 1865–1874Publication Date (Print):February 1, 1990Publication History Published online1 May 2002Published inissue 1 February 1990https://pubs.acs.org/doi/10.1021/ja00161a034https://doi.org/10.1021/ja00161a034research-articleACS PublicationsRequest reuse permissionsArticle Views370Altmetric-Citations95LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe electronic structure of highly anisotropic low-spin ferric porphyrin complexes based on single-crystal EPR measurementsDaryl. Inniss, S. Michael. Soltis, and Charles E. StrouseCite this: J. Am. Chem. Soc. 1988, 110, 17, 5644–5650Publication Date (Print):August 1, 1988Publication History Published online1 May 2002Published inissue 1 August 1988https://pubs.acs.org/doi/10.1021/ja00225a010https://doi.org/10.1021/ja00225a010research-articleACS PublicationsRequest reuse permissionsArticle Views393Altmetric-Citations81LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure of low-spin ferric porphyrins: single-crystal EPR evidence for pseudo-Jahn-Teller distortion in (tetraphenylporphinato)iron(III) bis(imidazole) cationsS. Michael. Soltis and Charles E. StrouseCite this: J. Am. Chem. Soc. 1988, 110, 9, 2824–2829Publication Date (Print):April 27, 1988Publication History Published online1 May 2002Published inissue 27 April 1988https://pubs.acs.org/doi/10.1021/ja00217a022https://doi.org/10.1021/ja00217a022research-articleACS PublicationsRequest reuse permissionsArticle Views367Altmetric-Citations45LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, structure, and reactions of chiral rhenium vinylidene and acetylide complexes of the formula [(.eta.5-C5H5)Re(NO)(PPh3)(X)]n+. Vinylidene complexes that are formed by stereospecific C.beta. electrophilic attack, exist as two Re=C=C geometric isomers, and undergo stereospecific C.alpha. nucleophilic attackDwayne R. Senn, Andrew. Wong, Alan T. Patton, Marianne. Marsi, Charles E. Strouse, and J. A. GladyszCite this: J. Am. Chem. Soc. 1988, 110, 18, 6096–6109Publication Date (Print):August 1, 1988Publication History Published online1 May 2002Published inissue 1 August 1988https://doi.org/10.1021/ja00226a026RIGHTS & PERMISSIONSArticle Views378Altmetric-Citations71LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPeroxo(tetraphenylporphinato)manganese(III) and chloro(tetraphenylporphinato)manganese(II) anions. Synthesis, crystal structures, and electronic structures.Reuel B. VanAtta, Charles E. Strouse, Louise Karle Hanson, and Joan Selverstone ValentineCite this: J. Am. Chem. Soc. 1987, 109, 5, 1425–1434Publication Date (Print):March 1, 1987Publication History Published online1 May 2002Published inissue 1 March 1987https://pubs.acs.org/doi/10.1021/ja00239a024https://doi.org/10.1021/ja00239a024research-articleACS PublicationsRequest reuse permissionsArticle Views975Altmetric-Citations144LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts