Origin of the n-type transport behavior of azafullerene encapsulated single-walled carbon nanotubes

The transport properties of C59N encapsulated semiconducting single-walled carbon nanotubes (SWCNTs) (C59N-peapod) are investigated. Transport measurements of the peapods in field effect transistors (FETs) reveal that ∼14% of the C59N-peapod sample shows n-type behavior even though the electronic properties of the host SWCNTs are similar to those of C60-peapods that exhibit only p-type property. First-principles electronic-structure calculations reveal that the unique transport behavior originates from the monomer form of C59N encapsulated in SWCNTs. The singly occupied (SO) state of C59N lies in the energy gap of the SWCNT and the energy of this state increases substantially when electrons are injected. Because of this shift to higher energy, the SO state acts as a shallow donor state for the conduction band of the nanotube, which leads to n-type behavior in FET measurements

Synthesis and Chemiluminescent Properties of Amino-Acylated luminol Derivatives Bearing Phosphonium Cations

[EN] The monitoring of reactive oxygen species in living cells provides valuable information on cell function and performance. Lately, the development of chemiluminescence-based reactive oxygen species monitoring has gained increased attention due to the advantages posed by chemiluminescence, including its rapid measurement and high sensitivity. In this respect, specific organelle-targeting trackers with strong chemiluminescence performance are of high importance. We herein report the synthesis and chemiluminescence properties of eight novel phosphonium-functionalized amino-acylated luminol and isoluminol derivatives, designed as mitochondriotropic chemiluminescence reactive oxygen species trackers. Three different phosphonium cationic moieties were employed (phenyl, p-tolyl, and cyclohexyl), as well as two alkanoyl chains (hexanoyl and undecanoyl) as bridges/linkers. Synthesis is accomplished via the acylation of the corresponding phthalimides, as phthalhydrazide precursors, followed by hydrazinolysis. This method was chosen because the direct acylation of (iso)luminol was discouraging. The new derivatives' chemiluminescence was evaluated and compared with that of the parent molecules. A relatively poor chemiluminescence performance was observed for all derivatives, with the isoluminol-based ones being the poorest. This result is mainly attributed to the low yield of the fluorescence species formation during the chemiluminescence oxidation reaction.This project was financially supported by the European Union's Horizon 2020 framework program for research and innovation under grant agreement no. 712921, as well as a Greek State Scholarships Foundation (I.K.Y.) fellowship to A.P.Pantelia, A.; Daskalaki, I.; Cuquerella Alabort, MC.; Rotas, G.; Miranda Alonso, MÁ.; Vougioukalakis, GC. (2019). Synthesis and Chemiluminescent Properties of Amino-Acylated luminol Derivatives Bearing Phosphonium Cations. Molecules. 24(21):1-16. https://doi.org/10.3390/molecules24213957S116242

Synthesis and chemiluminescent properties of amino-acylated luminol derivatives bearing phosphonium cations

The monitoring of reactive oxygen species in living cells provides valuable information on cell function and performance. Lately, the development of chemiluminescence-based reactive oxygen species monitoring has gained increased attention, due to the advantages posed by chemiluminescence, including its rapid measurement and high sensitivity. In this respect, specific organelle-targeting trackers with strong chemiluminescence performance are of high importance. We herein report the synthesis and chemiluminescence properties of eight novel phosphonium-functionalized amino-acylated luminol and isoluminol derivatives, designed as mitochondriotropic chemiluminescence reactive oxygen species trackers. Three different phosphonium cationic moieties were employed (phenyl, p-tolyl, and cyclohexyl), as well as two alkanoyl chains (hexanoyl and undecanoyl) as bridges/linkers. Synthesis is accomplished via the acylation of the corresponding phthalimides, as phthalhydrazide precursors, followed by hydrazinolysis. This method was chosen because the direct acylation of (iso)luminol was discouraging. The new derivatives’ chemiluminescence was evaluated and compared with that of the parent molecules. A relatively poor chemiluminescence performance was observed for all derivatives, with the isoluminol-based ones being the poorest. This result is mainly attributed to the low yield of the fluorescence species formation during the chemiluminescence oxidation reaction

Synthesis and chemiluminescent properties of amino-acylated luminol derivatives bearing phosphonium cations

The monitoring of reactive oxygen species in living cells provides valuable information on cell function and performance. Lately, the development of chemiluminescence-based reactive oxygen species monitoring has gained increased attention, due to the advantages posed by chemiluminescence, including its rapid measurement and high sensitivity. In this respect, specific organelle-targeting trackers with strong chemiluminescence performance are of high importance. We herein report the synthesis and chemiluminescence properties of eight novel phosphonium-functionalized amino-acylated luminol and isoluminol derivatives, designed as mitochondriotropic chemiluminescence reactive oxygen species trackers. Three different phosphonium cationic moieties were employed (phenyl, p-tolyl, and cyclohexyl), as well as two alkanoyl chains (hexanoyl and undecanoyl) as bridges/linkers. Synthesis is accomplished via the acylation of the corresponding phthalimides, as phthalhydrazide precursors, followed by hydrazinolysis. This method was chosen because the direct acylation of (iso)luminol was discouraging. The new derivatives’ chemiluminescence was evaluated and compared with that of the parent molecules. A relatively poor chemiluminescence performance was observed for all derivatives, with the isoluminol-based ones being the poorest. This result is mainly attributed to the low yield of the fluorescence species formation during the chemiluminescence oxidation reaction

Building a functionalizable, potent chemiluminescent agent: A rational design study on 6,8-substituted luminol derivatives

Luminol is a prominent chemiluminescent (CL) agent, finding applications across numerous fields, including forensics, immunoassays, and imaging. Different substitution patterns on the aromatic ring can enhance or decrease its CL efficiency. We herein report a systematic study on the synthesis and photophysics of all possible 6,8-disubstituted luminol derivatives bearing H, Ph, and/or Me substituents. Their CL responses are monitored at three pH values (8, 10, and 12), thus revealing the architecture with the optimum CL efficiency. The most efficient pattern is used for the synthesis of a strongly CL luminol derivative, bearing a functional group for further, straightforward derivatization. This adduct exhibits an unprecedented increase in chemiluminescence efficiency at pH=12, pH=10, and especially at pH=8 (closer to the biologically-relevant conditions), compared to luminol. Complementary work on the fluorescence of the emissive species, as well as quantum chemistry computations are employed for the rationalization of the observed results

Tuning the reorganization energy of electron transfer in supramolecular ensembles – metalloporphyrin, oligophenylenevinylenes, and fullerene – and the impact on electron transfer kinetics

Oligo(p-phenylenevinylene) (oPPV) wires of various lengths featuring pyridyls at one terminal and C60 moieties at the other, have been used as molecular building blocks in combination with porphyrins to construct a novel class of electron donor–acceptor architectures. These architectures, which are based on non-covalent, directional interactions between the zinc centers of the porphyrins and the pyridyls, have been characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. Complementary physico-chemical assays focused on the interactions between electron donors and acceptors in the ground and excited states. No appreciable electron interactions were noted in the ground state, which was being probed by electrochemistry, absorption spectroscopy, etc.; the electron acceptors are sufficiently decoupled from the electron donors. In the excited state, a different picture evolved. In particular, steady-state and time-resolved fluorescence and transient absorption measurements revealed substantial electron donor–acceptor interactions. These led, upon photoexcitation of the porphyrins, to tunable intramolecular electron-transfer processes, that is, the oxidation of porphyrin and the reduction of C60. In this regard, the largest impact stems from a rather strong distance dependence of the total reorganization energy in stark contrast to the distance independence seen for covalently linked conjugates

Σύνθεση πυρρολο-βενζαζεπινών, -βενζοδιαζεπινών, -βενζοτριαζοκινών και -κινοξαλινών από παράγωγα του πυρρολίου

In the present thesis we have presented the synthesis of pyrrolo[3 ,2 -c][l]benzazepines and pyrrolo[l,2-c][1.3]benzodiazepines from (2 -aminophenyl)(pyrrol-2 -yl)methanone 189 and pyrrolo[l,2 -[3,2-ο][1]βενζαζεπινών και πυρρολο[1,2-ε][1.3]βενζοδιαζεπινών από την (2-αμινοφαινυλο)(πυρρολ-2-υλο)μεθανόνη 189 και πυρρολο[1,2-β]κινοξαλινών και πυρρολο[1,2-^][1.3.6]βενζοτριαζοκινών από τα Ν-(αλκυΐο ή αρυλο)-1-(2-νιτροφαινυλχ))-1//-7Π>ρρολιο-2 -καρβοξαμίδια 243 και 246. Συγκεκριμένα η 189 αντιδρώντας με θειοφωσγένιο έδωσε την ισοθειοκυανική ένωση 190, η οποία παρουσία ανθρακικού καλίου κυκλοποιήθηκε προς την πυρρολο[1,2 -ο][1.3]βενζοδιαζεπίνη 199, ενώ παρουσία χλωριούχου αργιλίου (III) κυκλοποιήθηκε προς την πυρρολο[3,2-,/)[1.5]διαζοκίνη 208. Η μελέτη του μηχανισμού της αντίδρασης κατέληξε στο συμπέρασμα ότι παρουσία 1 ισοδυνάμου τριαιθυλαμίνης σχηματίζεται το καρβαμοϋλοχλωρίδιο 216, το οποίο συμπεριφέρεται ως χλωρίδιο δ-κέτο οξέος με αποτέλεσμα να υφίσταται με την κυκλική μορφή 217, η οποία αντιδρώντας με τη μη αντιδρώσασα 189 δίνει το προϊόν διμερισμού. Η 192 αντιδρώντας με τριφωσγένιο παρουσία 2 ισοδύναμων τριαιθυλαμίνης και στη συνέχεια προσθήκη ανθρακικού καλίου κυκλοποιήθηκε προς την πυρρολο[1,2 -c][l .3]βενζοδιαζεπίνη 221. Επίσης η 192 αντιδρώντας με τριφωσγένιο παρουσία 1 ισοδύναμου τριαιθυλαμίνης έδωσε σε χαμηλή απόδοση (λόγω εκτενούς πολυμερισμού εξαιτίας των όξινων συνθηκών) την πυρρολο[3,2-τ][1]βενζαζεπίνη 222, ενώ καλύτερη απόδοση επιτεύχθηκε όταν η αντίδραση έγινε παρουσία 2 ισοδύναμων τριαιθυλαμίνης καιχλωριούχου αργιλίου (III). Η πυρρολο[1,2-ο][1.3]βενζοδιαζεπίνη 199 επιλέχθηκε ως η κατάλληλη αρχική ένωση για τη σύνθεση της 224 και του ανάλογου VPA-985 225. Αναγωγική αποθείωση της 199 έδωσε την 226, οξείδωση της οποίας έδωσε την 224. Η 224 αποδείχθηκε εξαιρετικά δραστικήπαρουσία νερού με αποτέλεσμα τη μη αναστρέψιμη διάνοιξη του δακτυλίου προς το αμίδιο 227, υποδεικνύοντας ότι η 224 δεν μπορεί να έχει αλκολιωτική δράση στο DNA όπως η ανθραμυκίνη. Η 226 ανάχθηκε προς τη 228, στη θέση 6 της οποίας εισάχθηκε ο κατάλληλος υποκαταστάτης με σχηματισμό αμιδικών δεσμών, δίνοντας το επιθυμητό προϊόν 225. Τα καρβοξαμίδια 243α,γ και 246α-γ,ε παρουσία υδριδίου του νατρίου σε DMF έδωσαν μέσω απονιτροκυκλοποίησης τις πυρρολο[ 1,2~α]κινοξαλινόνες 247α-ζ. Πειράματα που έγιναν για τη διερεύνηση του μηχανισμού της αντίδρασης απέδειξαν ότι λαμβάνει χώρα και μετάθεση Smiles με αποτέλεσμα η κυκλοποίηση να γίνεται και από το αμιδικό και από το a πυρρολικό άζωτο, δίνοντας έτσι 2 προϊόντα. Τα προϊόντα 248α-δ της μετάθεσης Smiles των αμιδίων 243α,γ και 246α,γ απομονώθηκαν σε καλή απόδοση όταν η παραπάνω αντίδραση έγινε σε THF. Τα αμίδια 248α,δ ανάχθηκαν προς τις αμίνες 263α,β οι οποίες αντιδρώντας με θειοφωσγένιο έδωσαν τις ισοθειοκυανικές ενώσεις 264α,β. Μελέτη των φασμάτων NMR των ενώσεων 248α-δ, 263α,β και 264α,β καθώς και η κρυσταλλική δομή της 248α υπέδειξαν ότι τα μόρια αυτά έχουν διαμόρφωση ευνοϊκή για το σχηματισμό του πυρρολο[1,2-c][l 3.6]βενζοτριαζοκινικού δακτυλίου. Η 264α σε DMF παρουσία ανθρακικού καλίου έδωσε την πυρρολο[1,2-ο][1.3.6]βενζοτριαζοκίνη 265α ενώ η 264β κάτω από τις ίδιες συνθήκες έδωσε τηβενζομιδαζολθειόνη 267 μέσω ενδοκυκλικής αντίδρασης. Η 265β απομονώθηκε όταν η 264β αντέδρασε με υδρίδιο του νατρίου σε THF. Επίσης οι αμίνες 263α,β αντιδρώντας με τριφωσγένιο σε THF παρουσία υδριδίου του νατρίου έδωσαν τις αντίστοιχες πυρρολο[1,2-ε][1.3 .6 ]βενζοτριαζοκίνες 275α,β. Οι 265α,β και 275α,β είναι ευαίσθητες στη διάνοιξη του δακτυλίου λόγω της τάσης του μορίου, με τις β πολύ πιο ευαίσθητες από τις α. Τέλος προσπάθεια αναγωγής των αμιδίων 263α,β προς τις αμίνες 282α,β με λίθιο αργίλιο υδρίδιο, με απώτερο σκοπό τη σύνθεση πυρρολο[1,2-c][ 1.3.6]βενζοτριαζοκινών περιεχόντων έναν sp3 άνθρακα στον τριαζοκινικό δακτύλιο, είχε ως αποτέλεσμα το βενζιμιδαζόλιο 285 και το αμίδιο 287 αντίστοιχα