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1.
Nano Lett ; 24(7): 2125-2130, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38341872

RESUMEN

Semiconductor nanocrystals (NCs) with high elemental and structural complexity can be engineered to tailor for electronic, photovoltaic, thermoelectric, and battery applications etc. However, this greater complexity causes ambiguity in the atomic structure understanding. This in turn hinders the mechanistic studies of nucleation and growth, the theoretical calculations of functional properties, and the capability to extend functional design across complementary semiconductor nanocrystals. Herein, we successfully deciphered the atomic arrangements of 4 different nanocrystal domains in CuαZnßSnγSeδ (CZTSe) nanocrystals using crucial zone axis analysis on multiple crystals in different orientations. The results show that the essence of crystallographic progression from binary to multielemental semiconductors is actually the change of theoretical periodicity. This transition is caused by decreased symmetry in the crystal instead of previously assumed crystal deformation. We further reveal that these highly complex crystalline entities have highly ordered element arrangements as opposed to the previous understanding that their elemental orderings are random.

2.
Angew Chem Int Ed Engl ; 60(16): 8683-8688, 2021 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-33491265

RESUMEN

Quantum computing and quantum information processing (QC/QIP) crucially depend on the availability of suitable quantum bits (qubits) and methods of their manipulation. Most qubit candidates known to date are not applicable at ambient conditions. Herein, we propose radical-grafted mesoporous silica as a versatile and prospective nanoplatform for spin-based QC/QIP. Extremely stable Blatter-type organic radicals are used, whose electron spin decoherence time is profoundly long even at room temperature (up to Tm ≈2.3 µs), thus allowing efficient spin manipulation by microwave pulses. The mesoporous structure of such composites is nuclear-spin free and provides additional opportunities of embedding guest molecules into the channels. Robustness and tunability of these materials promotes them as highly promising nanoplatforms for future QC/QIP developments.

3.
Chemistry ; 26(1): 269-274, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31553081

RESUMEN

A metal-free, photoinduced aerobic tandem amine dehydrogenation/Povarov cyclization/aromatization reaction between N-aryl glycine esters and indoles leads to tetracyclic 11H-indolo[3,2-c]quinolines under mild conditions and with high yields. The reaction can be performed by using molecular iodine along with visible light, or by combining an organic photoredox catalyst with a halide anion. Mechanistic studies reveal that product formation occurs through a combination of radical-mediated oxidation steps with an iminium ion or N-haloiminium ion [4+2]-cycloaddition, and the N-heterocyclic products constitute new analogues of the antiplasmodial natural alkaloid isocryptolepine.

4.
Nervenarzt ; 91(10): 926-935, 2020 Oct.
Artículo en Alemán | MEDLINE | ID: mdl-32696077

RESUMEN

The relationship between headache and multiple sclerosis (MS) has been a matter of controversy for over 60 years. Headaches are still rated as a "red flag", indicating alternative diagnoses to MS, although in the last few years numerous studies have shown a frequent association between headache and MS. In recent studies on MS patients, a link was found between lower age/shorter disease duration of MS and frequent headaches. A study of 50 patients manifesting MS for the first time showed the highest headache prevalence in MS of 78% reported so far.Headaches can also be a possible side effect of most disease-modifying MS drugs. In many cases, however, the headache appears to be a symptom of MS in terms of secondary headache. This is also supported by pathophysiological implications, for example, by detecting B cell follicles in the meninges of MS patients.Migraine is the most common type of headache in MS. In some cases, this is a comorbidity of two diseases with many similarities, but headaches caused by inflammatory MS lesions also appear to be phenomenologically very similar to classic migraines; thus, distinguishing between them is often only successful with the help of thorough differential diagnostics (cerebrospinal fluid, MRI etc.).The task of future studies must be to specify the phenomenology of headache in MS even more precisely, in order to, to gain knowledge in, among others, patients with radiologically isolated syndrome, who often suffer from headache, because in these patients a considerable differential diagnostic and therapeutic uncertainty exists.


Asunto(s)
Trastornos Migrañosos , Esclerosis Múltiple , Cefalea/diagnóstico , Cefalea/epidemiología , Cefalea/etiología , Humanos , Imagen por Resonancia Magnética , Esclerosis Múltiple/complicaciones , Esclerosis Múltiple/diagnóstico , Prevalencia
5.
Angew Chem Int Ed Engl ; 59(30): 12450-12454, 2020 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-32501642

RESUMEN

Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido- and perhydroazepino[1,2-a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N-diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis.

6.
Mult Scler ; 25(12): 1618-1632, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-30657420

RESUMEN

BACKGROUND: Daclizumab is a monoclonal antibody that binds the high-affinity interleukin-2 receptor and was approved for the treatment of relapsing multiple sclerosis. Due to severe inflammatory brain disorders, the approval was suspended in March 2018. OBJECTIVE AND METHODS: This retrospective cohort study summarizes clinical, laboratory, radiological, and histological findings of seven patients who developed meningo-/encephalitis after daclizumab therapy. RESULTS: Patients presented with encephalitis and/or meningitis and suffered from systemic symptoms such as fever (5/7), exanthema (5/7), or gastrointestinal symptoms (4/7). Secondary autoimmune diseases developed. Blood analysis revealed an increase in eosinophils (5/7). Six patients fulfilled the diagnostic criteria for a drug reaction with eosinophilia and systemic symptoms (DRESS). Magnetic resonance imaging (MRI) showed multiple contrast-enhancing lesions, and enhancement of the ependyma (6/7), meninges (5/7), cranial or spinal nerves (2/7), and a vasculitic pattern (3/7). Histology revealed a pronounced inflammatory infiltrate consisting of lymphocytes, plasma cells and eosinophils, and densely infiltrated vessels. Most patients showed an insufficient therapeutic response and a high disability at last follow-up (median Expanded Disability Status Scale (EDSS) 8). Two patients died. CONCLUSION: Meningoencephalitis and DRESS may occur with daclizumab therapy. This potential lethal side effect is characterized by a dysregulated immune response. Our findings underline the importance of postmarketing drug surveillance.


Asunto(s)
Anticuerpos Monoclonales/efectos adversos , Daclizumab/efectos adversos , Encefalitis/inducido químicamente , Esclerosis Múltiple/tratamiento farmacológico , Adulto , Enfermedades Autoinmunes/tratamiento farmacológico , Encéfalo/efectos de los fármacos , Encéfalo/patología , Daclizumab/uso terapéutico , Encefalitis/patología , Femenino , Humanos , Inmunosupresores/efectos adversos , Inmunosupresores/uso terapéutico , Linfocitos/patología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
7.
J Neural Transm (Vienna) ; 126(2): 131-139, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30506270

RESUMEN

Multiple sclerosis (MS) is the most common immune-mediated inflammatory disease of the central nervous system (CNS). Early diagnosis and treatment is important to prevent progression of disability in the course of the chronic disease. Therefore, correct and fast identification of early symptoms is vital. Headache is generally not recognized as an early symptom of MS, although numerous studies could show a high prevalence of headache in MS patients. The most common misdiagnosis is migraine. The aim of this study is to investigate the prevalence as well as the phenomenology of headache in MS especially with regard to the progression of the disease. In a prospective, multicenter study, we unbiasedly recruited 150 patients with manifest MS based on the criteria of McDonald. 50 patients at the timepoint of initial diagnosis and 100 of them with a long-term course of the disease were included. Based on a semi-structured interview, we evaluated the occurrence of headache over the last 4 weeks as well as case history, clinical-neurological investigation and questionnaires about depression, fatigue, and quality of life. Prevalence of headache in all patients was 67%. Patients at the timepoint of symptom manifestation of MS showed the highest prevalence of headache that was ever been recorded of 78%. In general, patients with headache were younger, had a shorter duration of the disease, and were less physically affected. We noticed frequent occurrence of migraine and migraine-like headache. In the course of the disease, patients without disease-modifying drug (DMD) complained more frequently headaches than patients with any kind of therapy. Headache is an important early symptom of MS. This could be shown especially among 78% of patients with clinically isolated syndrome (CIS). Therefore, young people with frequent headache should undergo MRI of the head and in the case of abnormal findings a consecutive detailed differential diagnosis. This could reduce the latency until final diagnosis of MS, which is in general much too long. That way these patients could get the earliest possible treatment, which is important to stop the progression of the disease.


Asunto(s)
Progresión de la Enfermedad , Cefalea/etiología , Trastornos Migrañosos/etiología , Esclerosis Múltiple/complicaciones , Adolescente , Adulto , Femenino , Cefalea/diagnóstico , Cefalea/epidemiología , Humanos , Factores Inmunológicos , Masculino , Persona de Mediana Edad , Trastornos Migrañosos/diagnóstico , Trastornos Migrañosos/epidemiología , Esclerosis Múltiple/diagnóstico , Esclerosis Múltiple/tratamiento farmacológico , Esclerosis Múltiple/epidemiología , Prevalencia , Estudios Prospectivos , Adulto Joven
8.
Inorg Chem ; 58(13): 8471-8479, 2019 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-31184867

RESUMEN

Nanosized structural defects in metal-organic frameworks (MOFs) attract growing attention and often remarkably enhance functional properties of these materials for various applications. In this work, a series of MOFs [Cu2(TPTA)1- x(BDPBTR) x] (H4TPTA, [1,1':3',1″-terphenyl]-3,3'',5,5''-tetracarboxylic acid; H4BDPBTR, 1,3-bis(3,5-dicarboxyphenyl)-1,2,4-benzotriazin-4-yl radical)) with a new stable radical linker doped into the structure has been synthesized and investigated using Electron Paramagnetic Resonance (EPR). Mixed linkers H4TPTA and H4BDPBTR were used to bridge copper(II) paddle-wheel units into a porous framework, where H4BDPBTR is the close structural analogue of H4TPTA. MOFs with various x = 0-0.4 were investigated. EPR studies indicated that the radical linker binds to the copper(II) units differently compared to diamagnetic linker, resulting in the formation of nanosized structural defects. Moreover, remarkable kinetic phenomena were observed upon cooling of this MOF, where slow structural rearrangements and concomitant changes of magnetic interactions were induced. Thus, our findings demonstrate that doping of structurally mimicking radical linkers into MOFs represents an efficient approach for designing target nanosized defects and introducing new magnetostructural functionalities for a variety of applications.

9.
Phys Chem Chem Phys ; 21(6): 3122-3133, 2019 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-30675602

RESUMEN

The electric double layer formation of supercapacitors is governed by ion electrosorption at the electrode surface. Large surface areas are beneficial for the energy storage process, typically achieved by carbon electrode materials. It is a matter of debate whether pores provide the same contribution to the capacitance regardless of the size, or if subnanometer pores lead to an anomalous increase of capacitance. In our work, we developed a new model for normalized capacitance depending on pore sizes, using a combination of a sandwich type capacitor for micropores and double-cylinder capacitor model for larger pores. Modification factors for each capacitance value were calculated using the nonlinear generalized reduced gradient method to obtain a modified electric sandwich double-cylinder capacitor (ESDCC) model. The model was validated by comparing the measured capacitance values of a set of prepared activated carbons in organic electrolytes with simulated values according to the modified ESDCC model, using combined physisorption data of carbon dioxide and nitrogen. We concluded a non-constant capacitive contribution, with pores having the size of bare cations contributing to the capacitance to a larger extent and mesopores with the size of three solvated ions providing an unusual low contribution to the overall capacitance.

10.
J Am Chem Soc ; 140(16): 5330-5333, 2018 04 25.
Artículo en Inglés | MEDLINE | ID: mdl-29617560

RESUMEN

The synthesis of 3D covalent organic frameworks (COFs) adopting novel topologies is challenging, and so far 3D COFs have only been reported for nets based on building blocks with tetrahedral geometry. We demonstrate the targeted synthesis of an anionic 3D COF crystallizing in a three-coordinated srs net by exploiting a recently developed linkage for the formation of anionic silicate COFs based on hypercoordinate silicon nodes. The framework, named SiCOF-5, was synthesized by reticulating dianionic hexacoordinate [SiO6]2- nodes with triangular triphenylene building blocks and adopts a two-fold interpenetrated srs-c net with an overall composition of Na2[Si(C18H6O6)] (where C18H6O6 is triphenylene-2,3,6,7,10,11-hexakis(olate)). A key requirement for the crystallization of SiCOF-5 was the careful control over the nucleation and growth rate by gradual generation of the silicon source during the course of the reaction.

11.
Chemistry ; 24(40): 10253-10259, 2018 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-29750377

RESUMEN

Few natural oxindole alkaloids possess an exceptional spiro-[(1,3)oxazinan-3,6'-oxindole] core structure, which results from an unusual oxidative indole rearrangement. The Rauvolfia alkaloid reserpine can be converted into the spirooxindole-1,3-oxazines dioxyreserpine and trioxyreserpine through efficient visible-light catalytic photooxygenation with anthraquinone photocatalysts. A mechanistic investigation sheds new light on the photooxidative rearrangement of reserpine and related monoterpene indole alkaloids, and the spirooxindole-1,3-oxazine products can be valorized by reductive ring opening, to obtain cis-decahydroisoquinolines as new enantiopure synthetic building blocks, as demonstrated for dioxyreserpine.

12.
Eur Neurol ; 80(3-4): 115-120, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30368493

RESUMEN

AIMS: Headaches have not been considered a typical symptom of multiple sclerosis (MS), although since 2000, almost every study showed high prevalence. We screened 50 MS patients at the time of first occurrence of neurological symptoms and found the highest prevalence of headache in MS that was ever recorded (78%). Postmortem histological analyses of MS patients' brains revealed lymphoid follicle-like structures in the cerebral meninges and a pathophysiological link between headache, and high inflammatory activity especially in the initial phase of MS could be suspected. The aim of this study was to get insights into the persistence of headache in the further progress of the disease. METHODS: In a prospective, multicenter study, 50 MS patients at the time of first symptom manifestation were screened for the presence of headache within the last 4 weeks and again 6 months later with help of the Rostock Headache Questionnaire (Rokoko) as well as using the evaluation of case history and clinical-neurological investigation. RESULTS: We found a decrease of headache prevalence after 6 months from 78 to 61% (p = 0.01). We could also show a decrease of headache frequency, measured by days with headache in the last 4 weeks (9.5 vs. 5.9, p = 0.001). Migraine or probable migraine was the most frequent headache. In both investigations, the most frequent headache was recurrent pain with pulsating and throbbing character that lasted between 4 and 72 h. CONCLUSION: Headaches should be taken seriously as an important symptom in early MS. The decrease of headache 6 months after first symptom manifestation of MS could be a result of the immunomodulatory therapy. Young patients in whom migraine-like headaches occur should obligatory undergo an MRI of the head, and in the case of abnormal findings differential diagnosis should be initiated. This could reduce latency until final diagnosis of MS and enable early treatment.


Asunto(s)
Cefalea/epidemiología , Cefalea/etiología , Esclerosis Múltiple/complicaciones , Adulto , Encéfalo/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/diagnóstico , Esclerosis Múltiple/patología , Prevalencia , Estudios Prospectivos , Encuestas y Cuestionarios
13.
Angew Chem Int Ed Engl ; 57(51): 16683-16687, 2018 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-30334321

RESUMEN

We demonstrate the synthesis of the first anionic aluminum metal-organic framework (MOFs) constructed from tetrahedral AlO4 sites. Al-Td-MOF-1 was obtained in a simple two-step synthesis by condensation of 1,4-dihydroxybenzene and lithium aluminum hydride into an amorphous aluminate framework before applying a solvothermal treatment under basic conditions to obtain the crystalline Al-Td-MOF-1 with a chemical composition of Li[Al(C6 H4 O2 )2 ]. The overall Al-Td-MOF-1 structure consists of one-dimensional chains of alternating edge-sharing AlO4 and LiO4 tetrahedral sites describing unidirectional pore channels with a square window aperture of ≈5×5 Å2 , best described topologically as a uninodal 6-coordinated snp rod net. Al-Td-MOF-1 features the highest Li+ loading reported to date for a MOF (2.50 wt %) and proved to be an effective single-ion solid electrolyte. An ionic conductivity of 5.7×10-5  S cm-1 was measured for Al-Td-MOF-1 and the beneficial contribution of crystallinity was evidenced by an 8-fold increase in conductivity between the disordered and crystalline material.

14.
BMC Neurol ; 17(1): 156, 2017 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-28793876

RESUMEN

BACKGROUND: Patients with multiple sclerosis (MS) receiving long-term, subcutaneous interferon ß-1b (IFN ß-1b; Extavia®) often experience injection-site reactions and injection-site pain, which together with other side-effects (such as flu-like symptoms) result in suboptimal treatment compliance/adherence. The EXCHANGE study evaluated patient satisfaction with IFN ß-1b treatment, administered using ExtaviPro™ 30G, a new auto-injector, in a real-world setting. METHODS: This 26-week, open-label, prospective, non-interventional, observational, multi-country multi-centre study enrolled patients with MS who had been treated with IFN ß-1b or other disease-modifying therapies with a self-administered auto-injector for ≥3 months and who were planned to switch to IFN ß-1b treatment administered using ExtaviPro™ 30G as part of routine clinical care. Patient-reported outcomes included overall patient satisfaction (primary outcome) and satisfaction associated with treatment effectiveness, convenience and side-effects, assessed using Treatment Satisfaction Questionnaire for Medication (TSQM)-14. The changes in TSQM scores from baseline to Week 26 were reported. All data were analysed using SAS statistical software (version 9.4). RESULTS: Of the 336 patients enrolled, 324 were included in the analysis. At baseline, mean ± standard deviation (SD) age of patients was 41.8 ± 11.3 years and 68.2% were women. The mean ± SD of MS disease duration was 6.9 ± 6.6 years, and the majority of patients (94.1%) had relapsing-remitting MS. The mean ± SD of TSQM score for overall patient satisfaction at Week 26 was 75.6 ± 16.46 (baseline, 73.0 ± 17.14; p = 0.0342). The mean ± SD of TSQM subscale scores for patient satisfaction with effectiveness, side-effects and convenience were 75.0 ± 18.65 (baseline, 71.6 ± 19.45; p = 0.0356), 88.5 ± 18.98 (baseline, 82.7 ± 22.93; p = 0.0002) and 77.6 ± 16.72 (baseline, 71.1 ± 17.53; p < 0.0001), respectively. CONCLUSION: The results from this real-world study suggest that administering IFN ß-1b with the new ExtaviPro™ auto-injector significantly improves overall patient satisfaction, including satisfaction associated with effectiveness, side-effects and convenience in MS patients.


Asunto(s)
Interferon beta-1b/uso terapéutico , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple/tratamiento farmacológico , Satisfacción del Paciente , Adulto , Femenino , Humanos , Masculino , Cumplimiento de la Medicación , Persona de Mediana Edad , Medición de Resultados Informados por el Paciente , Estudios Prospectivos , Resultado del Tratamiento
15.
Microsc Microanal ; 23(3): 553-568, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28343460

RESUMEN

Statoliths are the only hard structures in the gelatinous bell of most scyphozoan medusae and investigations on these structures could promote investigations of the understudied population dynamics and phylogeny of jellyfish. We examined the statoliths of Aurelia aurita jellyfish of different ages by light microscopic and microtomographic measurements supplemented by scanning electron microscopy. The morphometric analyses confirmed that statolith numbers and sizes increase during jellyfish development and revealed that newly-formed statoliths had similar shapes that may change during statolith growth. Nevertheless, most statoliths had a typical compact rod shape with an aspect ratio of 1-2.5 at all ages and we suggest that the composition of statolith shapes may be taxa specific. We developed a new approach allowing exact measurements of statolith growth for the first time. The application of calcein as a fluorescent marker resulted in clear fluorescent lines within the statoliths, allowing calculations of the statolith side face growth increments (0.1 µm/day; n=252). A single-crystal analysis revealed that the calcein incubation did not affect the statolith crystal structure. In conclusion, calcein labeling is an excellent method to follow the growth of bassanite statoliths.

16.
Angew Chem Int Ed Engl ; 56(5): 1402-1406, 2017 01 24.
Artículo en Inglés | MEDLINE | ID: mdl-28067443

RESUMEN

A stereoselective synthesis of functionalized hexahydrocarbazoles was developed based on an unprecedented photoredox-induced dearomative radical (4+2)-cyclization/1,4-addition cascade between 3-(2-iodoethyl)indoles and acceptor-substituted alkenes. The title reaction simultaneously generates three C-C bonds and one C-H bond, along with three contiguous stereogenic centers. The hexahydro-1H-carbazole products are highly valuable intermediates for the synthesis of novel antibiotics, as well as unnatural ring homologues of polycyclic indoline alkaloids.

17.
Eur Neurol ; 75(5-6): 300-6, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27304890

RESUMEN

BACKGROUND: A marked proportion of multiple sclerosis (MS) relapses is followed by incomplete recovery. Our aim was to considerably increase the evidence of the clinical use of immunoadsorption (IA) as escalation therapy for patients with MS relapse. METHODS: A retrospective multicenter study was performed in MS patients with steroid refractory relapse who were treated with tryptophan IA. The main outcome parameter was change of acute relapse-related disability assessed by Expanded Disability Status Scale (EDSS) and visual acuity (VA) measurements for patients with optic neuritis (ON). IA treatments were performed using single-use tryptophan adsorbers. RESULTS: Data of 147 MS patients and 786 single IA treatments were analyzed. Treatment with IA was commenced in mean 32 ± 35 days after the onset of relapse. One hundred and five out of 147 patients (71.4%) improved functionally after mean 5.4 IA treatments within 7-10 days. EDSS improved from median 5 (interquartile range, IQR 3.5) to 4 (IQR 2.5) (p < 0.001). In patients with ON (n = 32), VA improved after the IA series in 84% of cases from median 0.2 (IQR 0.6) to 0.6 (IQR 0.66) (p < 0.001). In 98.9% of IA treatments, no clinically relevant side effect was reported. CONCLUSION: Tryptophan IA was found to be effective and well tolerated as escalation therapy for MS relapse.


Asunto(s)
Técnicas de Inmunoadsorción , Esclerosis Múltiple Recurrente-Remitente/terapia , Triptófano , Adulto , Resistencia a Medicamentos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Esteroides/uso terapéutico , Adulto Joven
18.
Chemistry ; 21(35): 12308-12, 2015 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-26211917

RESUMEN

A photocatalytic dearomatizative tandem [4+2] cyclization between N-(2-iodoethyl)indoles and a variety of alkenes leads to tri- and tetracyclic benzindolizidines with high diastereoselectivity and yield. The intermolecular annulation reaction is performed under visible-light irradiation and employs [Ir(ppy)3] or [Ir(dtbbpy)(ppy)2] PF6 as photocatalysts, in combination with tertiary amines as electron and hydrogen atom donors.

19.
Chemistry ; 21(1): 331-46, 2015 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-25352478

RESUMEN

Three-chromophore systems with light-harvesting behavior were prepared, which are based on periodic mesoporous organosilica (PMO) with crystal-like ordered structure. The organic bridges of biphenyl-PMO in the pore walls act as donors and two types of dye are incorporated in the one-dimensional channels. Consecutive two-step-Förster resonance energy transfer is observed from the biphenyl moieties to mediators (diethyl-aminocoumarin or aminoacridone), followed by energy transfer from mediators to acceptors (dibenzothiacarbocyanine, indodicarbocyanine, sulforhodamine G). High energy-transfer efficiencies ranging from 70 to 80 % are obtained for two-step-FRET, indicating that the mesochannel structure with one-dimensional ordering provides spatial arrangement of chromophore pairs for an efficient direct energy transfer. The emission wavelength can be tuned by a choice of acceptor dye: 477 nm (diethylaminocoumarin), 519 nm (aminoacridone), 567 nm (sulforhodamine G), 630 nm (dibenzothiacarbocyanine), and 692 nm (indodicarbocyanine).

20.
Chemistry ; 21(23): 8336-40, 2015 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-25917406

RESUMEN

A visible light-induced photocatalytic dehydrogenation/6π-cyclization/oxidation cascade converts 1-(nitromethyl)-2-aryl-1,2,3,4-tetrahydroisoquinolines into novel 12-nitro-substituted tetracyclic indolo[2,1-a]isoquinoline derivatives. Various photocatalysts promote the reaction in the presence of air and a base, the most efficient being 1-aminoanthraquinone in combination with K3 PO4 . Further, the 12-nitroindoloisoquinoline products can be accessed directly from C1-unfunctionalized 2-aryl-1,2,3,4-tetrahydroisoquinolines by extending the one-pot protocol with a foregoing photocatalytic cross-dehydrogenative coupling reaction, resulting in a quadruple cascade transformation.

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