1,721,041 research outputs found
Sintesi, caratterizzazione strutturale e attività biologica in vitro di organostagno(IV) con derivati di 1,2,4-triazolo[1,5-a]pirimidina
No full textSINTESI, CARATTERIZZAZIONE STRUTTURALE E ATTIVITÀ BIOLOGICA IN VITRO DI ORGANOSTAGNO(IV) CON DERIVATI DI 1,2,4-TRIAZOLO[1, 5-a]PIRIMIDINA
Maria Assunta Girasolo a, Simona Rubino a, Piera Sabatino b
aDip.to di Scienze e Tecnologie Molecolari e Biomolecolari, Università di Palermo, Viale delle Scienze, Palermo, Italy
bDip.to di Chimica G. Ciamician, Università di Bologna,via F. Selmi 2, Bologna, Italy
La struttura delle 1,2,4-triazolo[1,5-a]pirimidine1 è analoga a quella delle purine da cui differiscono per la presenza di un atomo di azoto pirimidinico in posizione “testa di ponte” e la scomparsa del protone acido dell’anello a cinque membri. Data la somiglianza tra questi sistemi, i composti di coordinazione delle 1,2,4-triazolo-[1,5-a]pirimidine possono essere considerati come sistemi modello per vari composti di coordinazione esistenti in natura. Recentemente sono stati sintetizzati e caratterizzati alcuni composti di diorganostagno(IV) con 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine2 (dptp), di cui viene qui riportata la struttura ai raggi X, e con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico.
Figura 1: Struttura cristallina e molecolare dell’addotto [n-Bu2SnCl2(dptp)] (1)
Il composto (1) presenta una coordinazione bipiramidale trigonale distorta intorno all’atomo di Sn; il legante dptp, che lega tramite N(3), occupa la posizione trans rispetto ad uno dei due atomi di Cl mentre le tre posizioni equatoriali sono occupate dal rimanente atomo di Cl e dai due leganti n-butilici. L’impaccamento tridimensionale della molecola è caratterizzato sia da un network di legami a H tra i gruppi C-H e gli atomi di Cl sia da interazioni aromatiche tra gli anelli aromatici presenti. L’attività citotossica di (1) è stata testata sulla linea cellulare umana U937 di linfoma istiocitico. Le cellule sono state trattate per 24 h in un range di concentrazioni compreso tra 0.5-20 μM dell’addotto (1), in comparazione al cisplatino. I risultati ottenuti hanno dimostrato che alla concentrazione di 20 μM, n-Bu2SnCl2(dptp) induce una marcata riduzione della vitalità cellulare che risulta essere del 5.5%, valore molto più basso del cisplatino, che alla stessa concentrazione risulta del 44%. Il composto è quindi più attivo del cisplatino. I complessi R2SnL2 sono stati ottenuti per reazione di R2SnO (R = Me, n-Bu, n-Oct ) con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico3 (HL) in metanolo a riflusso. La natura dei prodotti ottenuti è stata indagata analizzando i dati spettroscopici 1H-NMR, IR e 119Sn Mössbauer. Esaminando i parametri Mössbauer possiamo osservare che i valori di splitting di quadrupolo sono più grandi dei valori osservati in complessi di diorganostagno(IV) con geometria tetraedrica. Dobbiamo quindi presumere che lo stagno espanda il numero di coordinazione dando luogo a strutture bipiramidali trigonali, cis- o trans-R2, o ottaedriche trans-R2 fortemente distorte.
Bibliografia
1Salas,J.M.;Romero,M.A.;Sánchez,M.P.;Quirós,M.,Coord. Chem. Rev.,1999,1119,193. 2Girasolo,M.A.;Canfora,L.;Sabatino,P.;Schillaci,D.;Foresti,E.;Rubino,S.;Ruisi,G.;Stocco,G., J.Inorg.Biochem.,2012,106,156. 3Ruisi,G.,Canfora,L.;Bruno,G.;Rotondo,A.;Mastropietro, T.F.;Debbia,E.A.;Girasolo,M.A.;Megna,B., J.Organomet. Chem.,2010,695,546
LO SVILUPPO RURALE NELLE AREE IRPINE INVESTITE DALL'INIZIATIVA LEADER
No full textCartina Regione Campania
L'Asse IV del PSR della Campania, attraverso l'attivazione dei PSL - Piani di Sviluppo Locale elaborati e gestiti dai 13 GAL selezionati, si propone l'obiettivo di:
- rafforzare la capacità progettuale e la gestione locale;
- valorizzare le risorse endogene dei territori
Extra-special quotients of surface braid groups and double Kodaira fibrations with small signature
Full text linkWe study some special systems of generators on finite groups, introduced in
previous work by the first author and called "diagonal double Kodaira
structures", in order to investigate non-abelian, finite quotients of the pure
braid group on two strands , where is a
closed Riemann surface of genus . In particular, we prove that, if a finite
group admits a diagonal double Kodaira structure, then , and
equality holds if and only if is extra-special. In the last section, as a
geometrical application of our algebraic results, we construct two
-dimensional families of double Kodaira fibrations having signature .
Such surfaces are different from the ones recently constructed by Lee, L\"onne
and Rollenske and, as far as we know, they provide the first examples of
positive-dimensional families of double Kodaira fibrations with small
signature.Comment: 28 pages, 2 figures. Title changed. Final version, to appear in
Geometriae Dedicat
(more)SoftAssertions: A Progressive Paradigm for Urban Cultural Heritage, Interior Urbanism, and Contemporary Typologies
No full textThis chapter examines the shifting landscape of disciplines and professions, with particular focus towards “Spatial and Experience Design.” In spite of trends and increasing examples of the erosion and overlapping of disciplinary and professional boundaries, there is a need for some sort of disciplinary and professional definition. There needs to be a body of knowledge and skills defined and practiced and routes to circumvent them. This is especially relevant in a world of inter-, multi-, and trans-disciplinary work and comprehensive creative practices. The chapter examines core aspects of spatial/interior design and how this may intersect with other related disciplines and practices. An articulated interior urbanism creates clear areas of contribution from “interior” designers within the city. The chapter explores these cross-fertilizations through the curricular use of intensive design workshops (often of one-week duration) with a singular focus of the student's attention; selected student works from two such workshops at Politecnico di Milano are included
On factoriality of threefolds with isolated singularities
No full textWe investigate the existence of complete intersection threefolds X ⊂ ℙ<sup>n</sup> with only isolated, ordinary multiple points and we provide some sufficient conditions for their factoriality
Surfaces with surjective endomorphisms of any given degree
Full text linkWe present a complete classification of complex projective surfaces X with nontrivial self-maps (i.e. surjective morphisms f:X→X which are not isomorphisms) of any given degree. The starting point of our classification are results contained in Fujimoto and Nakayama that provide a list of surfaces that admit at least one nontrivial self-map. We then proceed by a case by case analysis that blends geometrical and arithmetical arguments in order to exclude that certain prime numbers appear as degrees of nontrivial self-maps of certain surfaces
MUSE – Mobile Urban Studio Experience: in the city, of the city, for the city
No full textThe Mobile Urban Studio Experience (MUSE) is a provoca- tion and proposal in, and beyond, education. It contributes to current discussions and processes on physical and digital space, education, and university life before, during, and post pandemic, and for a re-examina- tion of the relationships between the academy and the city/community, between the academy and the professional communities, and between the academy and the broader world. Hopefully MUSE might contribute to more nimble, responsive, resilient, and facile relationships amongst the creative professions and local and global communities in an ongoing manner of varying durations and in moments of peace, prosperity, crisis, or war.
MUSE can be an active contributor in the matter, and matters, of design culture. MUSE could create new cultures in design as well as affect issues, processes, and production of design and design culture. Further, MUSE underlines that design culture matters. And that the issues surrounding and forming design culture can be as important as the products, processes, people, and materials of design.
At this moment, MUSE, especially in its fullest and most complex triad modality, is still an embryonic creative tool, method, and system... a sort of creative Swiss-army-knife for education, professional practice, and social/humanitarian efforts and actions
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
Full text linkNon-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
Mössbauer 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 π–π stacking interactions between
pairs of antiparallel triazolopyrimidine rings mimick basepair
interactions physiologically occurring in DNA (Fig.1).
Mössbauer spectra suggest for Et2SnCl2(dbtp)2 a
distorted octahedral structure, with C-Sn-C bond angles
lower than 180°. 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 μg mL-1 against S. aureus ATCC29213 and also
resulted active against methicillin resistant S. epidermidis RP62A
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