Complexes of 21,23-dioxaporphyrin with neutral Zn, Cd, Hg, Cu, Ag, and Au atoms as well as some one-dimensional arrays of those complexes containing up to ten repeat units were modeled at the PBE/def2-TZVPP level of theory with D3 empirical dispersion correction. The binding energy between the metal atom and the macrocycle was found to vary from 90 kcal/mol for Cu to -14 kcal/mol for Hg. Strong charge transfer from the metal to the macrocycle accompanied complex formation. The complexes were able to form dimers and nanoarrays that were held together mostly by dispersion forces. Different types of dimers were studied: face-to-face (F) and two types of parallel-displaced ones. F dimers were calculated to be the lowest-energy structures for Cu and Ag systems. Nanoarray formation was studied for these complexes. The band gaps (Eg) of the nanoarrays were found to be smaller than 1 eV, and decreased slightly as the number of repeat units in the nanoaggregates increased. The ionization potentials and electron affinities were greatly affected by the number of repeat units due to the delocalization of polarons over the entire nanoarray. The polaron delocalization and the related reorganization energies depended to a considerable extent on the metal present in the complex. For the studied nanoarrays, the reorganization energies for hole and electron transport decreased linearly with 1/n, where n is the number of repeat units in the nanoaggregate; for an infinitely long chain, the reorganization energy was zero for electron transport and 0.03-0.04 eV for hole transport.
In this paper we describe our efforts towards building a framework that extends the functionality of an Open Access Repository by implementing processes that integrate the ongoing trends in social media into the context of a digital collection—while taking into account the potential of social media, the relevance of open infrastructures and the accessibility of open knowledge. We refer to these processes collectively as the Social Media Engine. The purpose of this paper is twofold: first, we propose to challenge some of the preconceived notions of digital libraries by making repositories more dynamic; and second, by challenging this notion we want to promote public engagement and open scholarship. As a work in progress, we believe that a real challenge lies in emphasizing the connections between documents that can be treated as objects of study as well.
T odo es cuestión de enfoque y de altura de miras signados por la creatividad, para poder comprender cómo la parte se entreteje con el todo y viceversa. Por supuesto que no resulta sencillo que la mente levante el vuelo para lograr un conocimiento integral de aquello que busca conocer. Con tenaz reincidencia la mente suele quedar varada en las situaciones inmediatas, en los aspectos particulares que ofrece la realidad. Pero esto que pudiera entenderse como una cierta normalidad en los individuos particulares cuando pretenden conocer el cotidiano entorno en el que están inmersos, se torna ciertamente preocupante dentro de una actividad sistemática y programática de conocimiento como la que se lleva a cabo dentro de una disciplina cognoscitiva. Lo que por otra parte, habla del nivel de avance en cuanto a la fundamentación de tal disciplina. Un ejemplo de esto lo representa la Bibliotecología en la cual una orientación cognoscitiva anclada en el conocimiento inmediato, particular y
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