Non-covalent interactions in organotin(IV) derivatives of 5,7-ditertbutyl- and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine as recognition motifs in crystalline self- assembly and their in vitro antistaphylococcal activity

Non-covalent interactions are known to play a key role in biological compounds due to their stabilization of the tertiary and quaternary structure of proteins [1]. Ligands similar to purine rings, such as triazolo pyrimidine ones, are very versatile in their interactions with metals and can act as model systems for natural bio-inorganic compounds [2]. A considerable series (twelve novel compounds are reported) of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) and 5,7-diphenyl- 1,2,4-triazolo[1,5-a]pyrimidine (dptp) were synthesized and investigated by FT-IR and 119Sn M\uf6ssbauer in the solid state and by 1H and 13C NMR spectroscopy, in solution [3]. The X-ray crystal and molecular structures of Et2SnCl2(dbtp)2 and Ph2SnCl2(EtOH)2(dptp)2 were described, in this latter pyrimidine molecules are not directly bound to the metal center but strictly H-bonded, through N(3), to the -OH group of the ethanol moieties. The network of hydrogen bonding and aromatic interactions involving pyrimidine and phenyl rings in both complexes drives their self-assembly. Noncovalent interactions involving aromatic rings are key processes in both chemical and biological recognition, contributing to overall complex stability and forming recognition motifs. It is noteworthy that in Ph2SnCl2(EtOH)2(dptp)2 \u3c0\u2013\u3c0 stacking interactions between pairs of antiparallel triazolopyrimidine rings mimick basepair interactions physiologically occurring in DNA (Fig.1). M\uf6ssbauer spectra suggest for Et2SnCl2(dbtp)2 a distorted octahedral structure, with C-Sn-C bond angles lower than 180\ub0. The estimated angle for Et2SnCl2(dbtp)2 is virtually identical to that determined by X-ray diffraction. Ph2SnCl2(EtOH)2(dptp)2 is characterized by an essentially linear C-Sn-C fragment according to the X-ray all-trans structure. The compounds were screened for their in vitro antibacterial activity on a group of reference staphylococcal strains susceptible or resistant to methicillin and against two reference Gramnegative pathogens [4] . We tested the biological activity of all the specimen against a group of staphylococcal reference strains (S. aureus ATCC 25923, S. aureus ATCC 29213, methicillin resistant S. aureus 43866 and S. epidermidis RP62A) along with Gram-negative pathogens (P. aeruginosa ATCC9027 and E. coli ATCC25922). Ph2SnCl2(EtOH)2(dptp)2 showed good antibacterial activity with a MIC value of 5 \u3bcg mL-1 against S. aureus ATCC29213 and also resulted active against methicillin resistant S. epidermidis RP62A

Street Furniture and the Nation State: A Global Process

In the popular imagination, street furniture has traditionally been understood as evoking a sense of national or local identity. From Paris’ metro entrances, DDR lampposts in Berlin, and London’s york stone pavements, the designed environment has been able to contribute to the unique qualities of a place. In some instances this was deliberate. In postwar Britain for instance, the Council of Industrial Design – a state-funded design organization - often appeared to measure the quality of street furniture on the basis of its national characteristics. On other occasions, the relationship between such objects and identity emerged accidentally. In Britain during the 1980s, for example, the replacement of Gilbert Scott's red telephone box with an alternative BT model provoked considerable debate. For many people, this act was not just a Conservative attack on nationalization and state-ownership, but also on the very fabric of British identity. This understanding of street furniture has retained its currency for many years, and cities across the world have used street furniture to provide a sense of visual coherency for neighbourhoods in need of new identities, strengthening their character and improving the public's relationship to them. In this way, street furniture has been employed as a cipher for the narrative of regeneration, in which - as a means of altering the identity of a space - street furniture can project a new face upon the street. Increasingly however, advertising companies are able to lever themselves into the street furniture market by offering to provide the service to the local authorities for free in return for advertising space. In offering this service, global companies like JC Decaux, Wall and Clear Channel command a huge amount of commercial power within the city. The excessive homogenization of street furniture coupled with the overwhelming presence of advertising which is increasingly sanctioned by local authorities keen to reduce costs, has resulted in the perception of poorer quality streets. Thus, the irony of regeneration is that by seeking to promote the unique identity of a city, many places often end up looking more and more alike. This paper will examine recent developments in the process by which the street is furnished and the agents responsible. It will specifically look at how these changes have affected the relationship between street furniture and identity, and equally the effect this process has had on understandings of national design histories. Clearly, evaluating contemporary street furniture through the lens of the nation-state is of very little value, since the international differences between street furniture are considerably less marked than they used to be. This extraordinary aesthetic convergence is partly linked to economies of scale - after all, just how many different kinds of bus stop can Europe afford to have? Yet it also reflects some of the challenges posed by globalization and privatization of public space. This paper will reflect upon that process, and how these bigger narratives increasingly affect the landscape of the street