University of Alicante

Abstract Gas adsorption is an important tool for the characterisation of porous solids and fine powders. Major advances in recent years have made it necessary to update the 1985 IUPAC manual on Reporting Physisorption Data for Gas/Solid Systems. The aims of the present document are to clarify and standardise the presentation, nomenclature and methodology associated with the application of physisorption for surface area assessment and pore size analysis and to draw attention to remaining problems in the interpretation of physisorption data.

ADVERTISEMENT RETURN TO ISSUEPREVArticleThe Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†Rafael Chinchilla and Carmen NájeraView Author Information Departamento de Química Orgánica and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Facultad de Ciencias, Apartado 99, 03080 Alicante, Spain Cite this: Chem. Rev. 2007, 107, 3, 874–922Publication Date (Web):February 17, 2007Publication History Received25 September 2006Published online17 February 2007Published inissue 1 March 2007https://pubs.acs.org/doi/10.1021/cr050992xhttps://doi.org/10.1021/cr050992xresearch-articleACS PublicationsCopyright © 2007 American Chemical SocietyRequest reuse permissionsArticle Views60007Altmetric-Citations2605LEARN 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 SUBJECTS:Anions,Catalysts,Hydrocarbons,Palladium,Sonogashira coupling reaction Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTHydroamination: Direct Addition of Amines to Alkenes and AlkynesThomas E. Müller*†, Kai C. Hultzsch*‡§, Miguel Yus∥§, Francisco Foubelo∥§, and Mizuki Tada⊥§View Author Information CAT Catalytic Center, ITMC, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany, Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087, Departamento de Química Orgánica, Universidad de Alicante, E-03080 Alicante, Spain, and Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan* To whom correspondence should be addressed. Phone: +49 241 80 28594. Fax: +49 241 80 22593. E-mail: [email protected]†RWTH Aachen.‡Rutgers University.∥Universidad de Alicante.⊥The University of Tokyo.§E-mail addresses: [email protected]; [email protected]; [email protected]; [email protected].Cite this: Chem. Rev. 2008, 108, 9, 3795–3892Publication Date (Web):August 26, 2008Publication History Received22 January 2008Published online26 August 2008Published inissue 10 September 2008https://pubs.acs.org/doi/10.1021/cr0306788https://doi.org/10.1021/cr0306788review-articleACS PublicationsCopyright © 2008 American Chemical SocietyRequest reuse permissionsArticle Views40285Altmetric-Citations1817LEARN 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 SUBJECTS:Amines,Catalysts,Cyclization,Hydrocarbons,Organic reactions Get e-Alerts

Immobilization of enzymes may produce alterations in their observed activity, specificity or selectivity. Although in many cases an impoverishment of the enzyme properties is observed upon immobilization (caused by the distortion of the enzyme due to the interaction with the support) in some instances such properties may be enhanced by this immobilization. These alterations in enzyme properties are sometimes associated with changes in the enzyme structure. Occasionally, these variations will be positive. For example, they may be related to the stabilization of a hyperactivated form of the enzyme, like in the case of lipases immobilized on hydrophobic supports via interfacial activation. In some other instances, these improvements will be just a consequence of random modifications in the enzyme properties that in some reactions will be positive while in others may be negative. For this reason, the preparation of a library of biocatalysts as broad as possible may be a key turning point to find an immobilized biocatalyst with improved properties when compared to the free enzyme. Immobilized enzymes will be dispersed on the support surface and aggregation will no longer be possible, while the free enzyme may suffer aggregation, which greatly decreases enzyme activity. Moreover, enzyme rigidification may lead to preservation of the enzyme properties under drastic conditions in which the enzyme tends to become distorted thus decreasing its activity. Furthermore, immobilization of enzymes on a support, mainly on a porous support, may in many cases also have a positive impact on the observed enzyme behavior, not really related to structural changes. For example, the promotion of diffusional problems (e.g., pH gradients, substrate or product gradients), partition (towards or away from the enzyme environment, for substrate or products), or the blocking of some areas (e.g., reducing inhibitions) may greatly improve enzyme performance. Thus, in this tutorial review, we will try to list and explain some of the main reasons that may produce an improvement in enzyme activity, specificity or selectivity, either real or apparent, due to immobilization.

Asymmetric multicomponent reactions involve the preparation of chiral compounds by the reaction of three or more reagents added simultaneously. This kind of addition and reaction has some advantages over classic divergent reaction strategies, such as lower costs, time, and energy, as well as environmentally friendlier aspects. All these advantages, together with the high level of stereoselectivity attained in some of these reactions, will force chemists in industry as in academia to adopt this new strategy of synthesis, or at least to consider it as a viable option. The positive aspects as well as the drawbacks of this strategy are discussed in this Review.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransition-Metal-Catalyzed Addition of Heteroatom−Hydrogen Bonds to AlkynesFrancisco Alonso, Irina P. Beletskaya, and Miguel YusView Author Information Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain, and Department of Chemistry, Lomonosov Moscow State University, Vorob'evy Gory, 119992 Moscow, Russia Cite this: Chem. Rev. 2004, 104, 6, 3079–3160Publication Date (Web):April 14, 2004Publication History Received23 October 2003Published online14 April 2004Published inissue 1 June 2004https://pubs.acs.org/doi/10.1021/cr0201068https://doi.org/10.1021/cr0201068research-articleACS PublicationsCopyright © 2004 American Chemical SocietyRequest reuse permissionsArticle Views16553Altmetric-Citations1494LEARN 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 SUBJECTS:Catalysts,Cyclization,Hydrocarbons,Organic compounds,Organic reactions Get e-Alerts

Abstract Enzyme biocatalysis plays a very relevant role in the development of many chemical industries, e.g., energy, food or fine chemistry. To achieve this goal, enzyme immobilization is a usual pre‐requisite as a solution to get reusable biocatalysts and thus decrease the price of this relatively expensive compound. However, a proper immobilization technique may permit far more than to get a reusable enzyme; it may be used to improve enzyme performance by improving some enzyme limitations: enzyme purity, stability (including the possibility of enzyme reactivation), activity, specificity, selectivity, or inhibitions. Among the diverse immobilization techniques, the use of pre‐existing supports to immobilize enzymes (via covalent or physical coupling) and the immobilization without supports [enzyme crosslinked aggregates (CLEAs) or crystals (CLECs)] are the most used or promising ones. This paper intends to give the advantages and disadvantages of the different existing immobilization strategies to solve the different aforementioned enzyme limitations. Moreover, the use of nanoparticles as immobilization supports is achieving an increasing importance, as the nanoparticles versatility increases and becomes more accessible to the researchers. We will also discuss here some of the advantages and drawbacks of these non porous supports compared to conventional porous supports. Although there are no universal optimal solutions for all cases, we will try to give some advice to select the optimal strategy for each particular enzyme and process, considering the enzyme properties, nature of the process and of the substrate. In some occasions the selection will be compulsory, for example due to the nature of the substrate. In other cases the optimal biocatalyst may depend on the company requirements (e.g., volumetric activity, enzyme stability, etc).

Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated CRISPR-associated sequence (CAS) proteins constitute a novel antiviral defence system that is widespread in prokaryotes. Repeats are separated by spacers, some of them homologous to sequences in mobile genetic elements. Although the whole process involved remains uncharacterized, it is known that new spacers are incorporated into CRISPR loci of the host during a phage challenge, conferring specific resistance against the virus. Moreover, it has been demonstrated that such interference is based on small RNAs carrying a spacer. These RNAs would guide the defence apparatus to foreign molecules carrying sequences that match the spacers. Despite this essential role, the spacer uptake mechanism has not been addressed. A first step forward came from the detection of motifs associated with spacer precursors (proto-spacers) of Streptococcus thermophilus, revealing a specific recognition of donor sequences in this species. Here we show that the conservation of proto-spacer adjacent motifs (PAMs) is a common theme for the most diverse CRISPR systems. The PAM sequence depends on the CRISPR-CAS variant, implying that there is a CRISPR-type-specific (motif-directed) choice of the spacers, which subsequently determines the interference target. PAMs also direct the orientation of spacers in the repeat arrays. Remarkably, observations based on such polarity argue against a recognition of the spacer precursors on transcript RNA molecules as a general rule.

The coupling of aryl or vinyl halides with terminal acetylenes catalysed by palladium and other transition metals, commonly termed as Sonogashira cross-coupling reaction, is one of the most important and widely used sp(2)-sp carbon-carbon bond formation reactions in organic synthesis, frequently employed in the synthesis of natural products, biologically active molecules, heterocycles, molecular electronics, dendrimers and conjugated polymers or nanostructures. This critical review focuses on developments in the Sonogashira reaction achieved in recent years concerning catalysts, reaction conditions and substrates (352 references).

A set of terms, definitions, and recommendations is provided for use in the classification of coordination polymers, networks, and metal–organic frameworks (MOFs). A hierarchical terminology is recommended in which the most general term is coordination polymer. Coordination networks are a subset of coordination polymers and MOFs a further subset of coordination networks. One of the criteria an MOF needs to fulfill is that it contains potential voids, but no physical measurements of porosity or other properties are demanded per se. The use of topology and topology descriptors to enhance the description of crystal structures of MOFs and 3D-coordination polymers is furthermore strongly recommended.

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTHydrogen Autotransfer in the N-Alkylation of Amines and Related Compounds using Alcohols and Amines as ElectrophilesGabriela Guillena*, Diego J. Ramón*, and Miguel Yus*View Author Information Instituto de Síntesis Orgánica and Departamento de Química Orgánica, Universidad de Alicante, Facultad de Ciencias, Apartado 99, E-03080 Alicante, Spain* Phone: +34 965903986. Fax: +34 965903549. E-mail: [email protected]; [email protected]; [email protected]. URLs: http://iso.ua.es/ and http://www.ua.es/dept.quimorg/index.html.Cite this: Chem. Rev. 2010, 110, 3, 1611–1641Publication Date (Web):November 23, 2009Publication History Received8 June 2009Published online23 November 2009Published inissue 10 March 2010https://pubs.acs.org/doi/10.1021/cr9002159https://doi.org/10.1021/cr9002159review-articleACS PublicationsCopyright © 2009 American Chemical SocietyRequest reuse permissionsArticle Views16919Altmetric-Citations1109LEARN 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 SUBJECTS:Alcohols,Amines,Catalysts,Hydrogen,Reaction products Get e-Alerts

Aridity, which is increasing worldwide because of climate change, affects the structure and functioning of dryland ecosystems. Whether aridification leads to gradual (versus abrupt) and systemic (versus specific) ecosystem changes is largely unknown. We investigated how 20 structural and functional ecosystem attributes respond to aridity in global drylands. Aridification led to systemic and abrupt changes in multiple ecosystem attributes. These changes occurred sequentially in three phases characterized by abrupt decays in plant productivity, soil fertility, and plant cover and richness at aridity values of 0.54, 0.7, and 0.8, respectively. More than 20% of the terrestrial surface will cross one or several of these thresholds by 2100, which calls for immediate actions to minimize the negative impacts of aridification on essential ecosystem services for the more than 2 billion people living in drylands.

Heterogeneous single-site catalysts consist of isolated, well-defined, active sites that are spatially separated in a given solid and, ideally, structurally identical. In this review, the potential of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) as platforms for the development of heterogeneous single-site catalysts is reviewed thoroughly. In the first part of this article, synthetic strategies and progress in the implementation of such sites in these two classes of materials are discussed. Because these solids are excellent playgrounds to allow a better understanding of catalytic functions, we highlight the most important recent advances in the modelling and spectroscopic characterization of single-site catalysts based on these materials. Finally, we discuss the potential of MOFs as materials in which several single-site catalytic functions can be combined within one framework along with their potential as powerful enzyme-mimicking materials. The review is wrapped up with our personal vision on future research directions.

This review focuses on important aspects of applying physisorption for the pore structural characterization of hierarchical materials such as mesoporous zeolites. During the last decades major advances in understanding the adsorption and phase behavior of fluids confined in ordered nanoporous materials have been made, which led to major progress in the physisorption characterization methodology (summarized in the 2015 IUPAC report on physisorption characterization). Here we discuss progress and challenges for the physisorption characterization of nanoporous solids exhibiting various levels of porosity from micro- to macropores. While physisorption allows one to assess micro- and mesopores, a widely employed method for textural analysis of macroporous materials is mercury porosimetry and we also review important insights associated with the underlying mechanisms governing mercury intrusion/extrusion experiments. Hence, although the main focus of this review is on physical adsorption, we strongly emphasize the importance of combining advanced physical adsorption with other complementary experimental techniques for obtaining a reliable and comprehensive understanding of the texture of hierarchically structured materials.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetal-Mediated Reductive Hydrodehalogenation of Organic HalidesFrancisco Alonso, Irina P. Beletskaya, and Miguel YusView Author Information Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain, and Laboratory of Organoelement Chemistry, Department of Chemistry, Moscow State University, GSP-3 Leninskie Gory, 119899 Moscow, Russia Cite this: Chem. Rev. 2002, 102, 11, 4009–4092Publication Date (Web):October 9, 2002Publication History Received7 March 2002Published online9 October 2002Published inissue 1 November 2002https://pubs.acs.org/doi/10.1021/cr0102967https://doi.org/10.1021/cr0102967research-articleACS PublicationsCopyright © 2002 American Chemical SocietyRequest reuse permissionsArticle Views15727Altmetric-Citations784LEARN 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 SUBJECTS:Anions,Aromatic compounds,Catalysts,Halogens,Inorganic compounds Get e-Alerts

When plants are attacked by pathogens, they defend themselves with an arsenal of defence mechanisms, both passive and active. The active defence responses, which require de novo protein synthesis, are regulated through a complex and interconnected network of signalling pathways that mainly involve three molecules, salicylic acid (SA), jasmonic acid (JA), and ethylene (ET), and which results in the synthesis of pathogenesis-related (PR) proteins. Microbe or elicitor-induced signal transduction pathways lead to (i) the reinforcement of cell walls and lignification, (ii) the production of antimicrobial metabolites (phytoalexins), and (iii) the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Among the proteins induced during the host plant defence, class III plant peroxidases (EC 1.11.1.7; hydrogen donor: H(2)O(2) oxidoreductase, Prxs) are well known. They belong to a large multigene family, and participate in a broad range of physiological processes, such as lignin and suberin formation, cross-linking of cell wall components, and synthesis of phytoalexins, or participate in the metabolism of ROS and RNS, both switching on the hypersensitive response (HR), a form of programmed host cell death at the infection site associated with limited pathogen development. The present review focuses on these plant defence reactions in which Prxs are directly or indirectly involved, and ends with the signalling pathways, which regulate Prx gene expression during plant defence. How they are integrated within the complex network of defence responses of any host plant cell will be the cornerstone of future research.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTChemicals from Alkynes with Palladium CatalystsRafael Chinchilla* and Carmen Nájera*View Author Information Departamento de Química Orgánica, Facultad de Ciencias, and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apartado 99, 03080 Alicante, Spain*Phone: +34 965903548. Fax: +34 965903549. E-mail: [email protected] (R.C.); [email protected] (C.N.).Cite this: Chem. Rev. 2014, 114, 3, 1783–1826Publication Date (Web):June 21, 2013Publication History Received28 February 2013Published online21 June 2013Published inissue 12 February 2014https://pubs.acs.org/doi/10.1021/cr400133phttps://doi.org/10.1021/cr400133preview-articleACS PublicationsCopyright © 2013 American Chemical SocietyRequest reuse permissionsArticle Views25435Altmetric-Citations865LEARN 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 SUBJECTS:Anions,Catalysts,Hydrocarbons,Palladium,Solvents Get e-Alerts

Global warming issues and the medium-term depletion of fossil fuel reserves are stimulating researchers around the world to find alternative sources of energy and organic carbon. Biomass is considered by experts the only sustainable source of energy and organic carbon for our industrial society, and it has the potential to displace petroleum in the production of chemicals and liquid transportation fuels. However, the transition from a petroleum-based economy to one based on biomass requires new strategies since the petrochemical technologies, well-developed over the last century, are not valid to process the biomass-derived compounds. Unlike petroleum feedstocks, biomass derived platform molecules possess a high oxygen content that gives them low volatility, high solubility in water, high reactivity and low thermal stability, properties that favour the processing of these resources by catalytic aqueous-phase technologies at moderate temperatures. This tutorial review is aimed at providing a general overview of processes, technologies and challenges that lie ahead for a range of different aqueous-phase transformations of some of the key biomass-derived platform molecules into liquid fuels for the transportation sector and related high added value chemicals.

Glutaraldehyde is one of the most widely used reagents in the design of biocatalysts. It is a powerful crosslinker, able to react with itself, with the advantages that this may bring forth. In this review, we intend to give a general vision of its potential and the precautions that must be taken when using this effective reagent. First, the chemistry of the glutaraldehyde/amino reaction will be commented upon. This reaction is still not fully clarified, but it seems to be based on the formation of 6-membered heterocycles formed by 5 C and one O. Then, we will discuss the production of intra- and inter-molecular enzyme crosslinks (increasing enzyme rigidity or preventing subunit dissociation in multimeric enzymes). Special emphasis will be placed on the preparation of cross-linked enzyme aggregates (CLEAs), mainly in enzymes that have low density of surface reactive groups and, therefore, may be problematic to obtain a final solid catalyst. Next, we will comment on the uses of glutaraldehyde in enzymes previously immobilized on supports. First, the treatment of enzymes immobilized on supports that cannot react with glutaraldehyde (only inter and intramolecular cross-linkings will be possible) to prevent enzyme leakage and obtain some enzyme stabilization via cross-linking. Second, the cross-linking of enzymes adsorbed on aminated supports, where together with other reactions enzyme/support crosslinking is also possible; the enzyme is incorporated into the support. Finally, we will present the use of aminated supports preactivated with glutaraldehyde. Optimal glutaraldehyde modifications will be discussed in each specific case (one or two glutaraldehyde molecules for amino group in the support and/or the protein). Using preactivated supports, the heterofunctional nature of the supports will be highlighted, with the drawbacks and advantages that the heterofunctionality may have. Particular attention will be paid to the control of the first event that causes the immobilization depending on the experimental conditions to alter the enzyme orientation regarding the support surface. Thus, glutaraldehyde, an apparently old fashioned reactive, remains the most widely used and with broadest application possibilities among the compounds used for the design of biocatalyst.