200809-09-2Relevant articles and documents
Photoinduced charge transfer in a conformational switching chlorin dimer-azafulleroid in polar and nonpolar media
Nikkonen, Taru,Muuronen, Mikko,Helaja, Juho,Oliva, Mara Moreno,Kahnt, Axel,Guldi, Dirk M.
, p. 590 - 600 (2015)
In the present study, a biomimetic reaction center model, that is, a molecular triad consisting of a chlorin dimer and an azafulleroid, is synthesized and its photophysical properties are studied in comparison with the corresponding molecular dyad, which consists only of a chlorin monomer and an azafulleroid. As evidenced by 1H NMR, UV/Vis, and fluorescence spectroscopy, the chlorin dimer-azafulleroid folds in nonpolar media into a C2-symmetric geometry through hydrogen bonding, resulting in appreciable electronic interactions between the chlorins, whereas in polar media the two chlorins diverge from contact. Femtosecond transient absorption spectroscopy studies reveal longer charge-separated states for the chlorin dimer-azafulleroid; 1.6 ns in toluene, compared with the lifetime of ≈0.9 ns for the corresponding chlorin monomer-azafulleroid in toluene. In polar media, for example, benzonitrile, similar charge-separated states are observed, but the lifetimes are inevitably shorter: 65 and 73 ps for the dimeric and monomeric chlorin-azafulleroids, respectively. Nanosecond transient absorption and singlet oxygen phosphorescence studies corroborate that in toluene, the charge-separated state decays indirectly via the triplet excited state to the ground state, whereas in benzonitrile, direct recombination to the ground state is observed. Complementary DFT studies suggest two energy-minima conformations, that is, a folded chlorin dimer-azafulleroid, which is present in nonpolar media, and another conformation in polar media, in which the two hydrophobic chlorins wrap the azafulleroid. Inspection of the frontier molecular orbitals shows that in the folded conformation, the HOMO on each chlorin is equivalent and is shared owing to partial π-π overlap, resulting in delocalization of the conjugated π electrons, whereas the wrapped conformation lacks this stabilization. As such, the longer charge-separated lifetime for the dimer is rationalized by both the electron donor-acceptor separation distance and the stabilization of the radical cation through delocalization. The chlorin folding seems to change the photophysical properties in a manner similar to that observed in the chlorophyll dimer in natural photosynthetic reaction centers.
Delayed release singlet oxygen sensitizers based on pyridone-appended porphyrins
Callaghan, Susan,Filatov, Mikhail A.,Sitte, Elisabeth,Savoie, Huguette,Boyle, Ross W.,Flanagan, Keith J.,Senge, Mathias O.
, p. 1371 - 1374 (2017/09/23)
A new type of porphyrin photosensitizer capable of generating singlet oxygen upon irradiation, storing it through binding to pyridone subunits, followed by slow release at 20-40 °C, is reported. The timescale of singlet oxygen release can be varied depend
Copper(II) complexes of three isomeric bis(tacn) ligands: Syntheses, structures and properties
Coghlan, Campbell J.,Campi, Eva M.,Batten, Stuart R.,Jackson, W. Roy,Hearn, Milton T.W.
, p. 246 - 252 (2016/01/26)
Two new isomeric bis(tacn) ligands, 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)-1-(hydroxymethyl)-benzene (HLhyx) and 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)anisole (Lanx) have been synthesised. In addition, 2,6-bis(1,4,7-triazacyclono
Efficient synthesis of small-sized phosphonated dendrons: Potential organic coatings of iron oxide nanoparticles
Garofalo, Antonio,Parat, Audrey,Bordeianu, Catalina,Ghobril, Cynthia,Kueny-Stotz, Marie,Walter, Aurlie,Jouhannaud, Julien,Begin-Colin, Sylvie,Felder-Flesch, Delphine
, p. 5226 - 5239 (2014/12/10)
We report herein the synthesis of biocompatible small-sized phosphonated monomers and dendrons used as functional coatings of metal oxide nanoparticles, more specifically superparamagnetic iron oxides (SPIOs) for magnetic resonance imaging (MRI) and therapy through hyperthermia. The molecules were engineered to modulate their size, their hydrophilic and/or biocompatible character (poly(amido)amine versus oligoethyleneglycol), the number of anchoring phosphonate groups (monophosphonate versus phosphonic tweezers) and the number of peripheral functional groups for further grafting of dyes or specific vectors. Such a library of hydrophilic phosphonic acids opens new possibilities for the investigation of dendronized nanohybrids as theranostics.
A bisphosphonate tweezers and clickable PEGylated PAMAM dendrons for the preparation of functional iron oxide nanoparticles displaying renal and hepatobiliary elimination
Ghobril, Cynthia,Popa, Gabriela,Parat, Audrey,Billotey, Claire,Taleb, Jacqueline,Bonazza, Pauline,Begin-Colin, Sylvie,Felder-Flesch, Delphine
, p. 9158 - 9160 (2013/09/24)
The functionalization of superparamagnetic iron oxide nanoparticles (SPION) with PEGylated PAMAM dendrons through a bisphosphonate tweezers yielded 15 and 30 nm dendritic nano-objects stable in physiological media and showing both renal and hepatobiliary
Rapid and efficient solvent-free synthesis of cyclophanes based on bipyridinium under mechanical ball milling
Xi, Hai-Tao,Zhao, Ting,Sun, Xiao-Qiang,Miao, Chun-Bao,Zong, Ting,Meng, Qi
, p. 691 - 694 (2013/03/28)
We reported here the first rapid and solvent-free template-directed preparation of cyclophanes based on bipyridinium, which was achieved using mechanical ball milling. The method affords a new strategy for construction of diverse substituted CBPQT·4PF6, which greatly shortens the reaction period, rendering this methodology practical in the field of supermolecular chemistry.
HIV-1 X4 activities of polycationic Viologen based dendrimers by interaction with the chemokine receptor CXCR4: Study of structure-activity relationship
Asaftei, Simona,Huskens, Dana,Schols, Dominique
supporting information, p. 10405 - 10413 (2013/02/23)
A series of viologen based dendrimers with polycationic scaffold carrying 10, 18, 26, 42, and 90 charges per molecule were used to determine the structure-activity relationship (SAR) with regard to HIV-1 inhibitory activity. The studies involved five comp
Viologen-based benzylic dendrimers: selective synthesis of 3,5-bis(hydroxymethyl)benzylbromide and conformational analysis of the corresponding viologen dendrimer subunit
Kathiresan, Murugavel,Walder, Lorenz,Ye, Fei,Reuter, Hans
supporting information; experimental part, p. 2188 - 2192 (2010/06/19)
Convergent and divergent strategies for the synthesis of viologen dendrimers with 1,3,5-tri-methylene-branching units are discussed. The title compound is easily transformed into 1-[3,5-bis(hydroxymethyl)benzyl]-4-(pyridin-4-yl)pyridinium hexafluorophosphate, which is used in sequential growth and activation steps as a CB2 compound in the cascade-type dendrimer synthesis (B = -OH, activation = -OH → Br). Analysis of the dendrimer structure reveals that three torsional angles, that is, τ1 between the two pyridinium units, τ2 between the methylene and pyridinium and τ3 between the methylene and phenyl, determine the conformational space of the dendrimers. We report here the crystal structure of 1-[3,5-bis(hydroxymethyl)benzyl]-4-(pyridin-4-yl)pyridinium as PF6- salt which represents the smallest subunit of the dendrimer that shows the same three torsional angles. The crystal structure together with the results from PM3 calculations opens an avenue to judge the structure of benzylic viologen-based dendrimers.
"viologen"dendrimers as antiviral agents: The effect of charge number and distance
Asaftei, Simona,De Clercq, Erik
supporting information; experimental part, p. 3480 - 3488 (2010/09/04)
A series of "viologen"derivatives (4,4′-bipyridinium salts) carrying between 1 and 90 charges per molecule have been prepared and investigated for their activity against human immunodeficiency virus (HIV), herpes simplex virus (HSV), vesicular stomatitis, Punta Toro virus, Sindbis virus, Reovirus, and respiratory syncytial viruses. In general, most of the compounds showed good activities against HIV-1 (strain IIIB). In particular, compound 36 exhibited the highest in vitro activity and selectivity index against HIV-1 (strain IIIB) (EC50 = 0.26 ± 0.08 μM, SI = 75.7) in MT-4 cells. The results imply that the antiviral activity requires an optimal number and distance of the positive charges.
Synthesis and supramolecular properties of a novel octaphosphonate porphyrin
Bhosale, Sheshanath V.,Kalyankar, Mohan B.,Langibrd, Steven J.,Bhosale, Sidhanath V.,Oliver, Ruth F.
scheme or table, p. 4128 - 4134 (2009/12/26)
Two complementary routes were developed for preparing novel octaphosphonate porphyrins. The use of protected/deprotected phosphonate-substituted precursors in the rational synthesis gave an overall yield 16%. A more streamlined synthetic path gave 21 % overall yield, of the target molecule. Octaphosphonate porphyrin possesses promising properties in supramolecular aggregate formation with cyclam. Cofacial reversible self-assembly of a meso-substituted octaphosphonate porphyrin with cyclam yields micrometer-long nanowires with a height of about 1-1.5 nm. The resulting wires were characterized by UV/Vis absorption, emission and atomic force microscopy and transmission electron microscopy. ( Wiley-VCH Verlag GmbH & Co. KGaA.
