Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• causes the observed fluorescence decrease. The optical parameters of all 4 dyes, including absorption maxima (λmax,abs), fluorescence emission maxima (λmax,f), hypsochromic shift of the absorption maxima (Δλmax), and fluorescence quantum yields (Φf) for different excitation wavelengths, obtained for the

• TDPBE0 spectra in ACN for dye 4b and its Ba2+ complex. Quaternization of 2-methylbenzothiazoles with alkane sultones. Synthesis of 4-(aza-15-crown-5)benzocarbaldehyde (3) [22]. Synthesis of dyes 4a–d. Absorption maxima (λmax,abs), fluorescence emission maxima (λmax,f), shift of the absorption maxima

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• , compounds P and B alone only displayed fairly feeble fluorescence emission. Upon addition of 2,2’-CBP4, the fluorescence intensity was remarkably improved more than 600 times (Figure 2 and Supporting Information File 1, Figure S10). This was due to the effect of lowering polar microenvironment when P or B

• delivery, supramolecular amphiphiles, etc. Experimental 2,2’-OEtBP4 was synthesized according to our previously reported method [47]. P and B were purchased from Shanghai Aladdin Bio-Chem Technology Co.,LTD. 1H NMR and 13C NMR spectra were recorded on a Bruker AV500 instrument. The fluorescence emission

• presence of 2,2’-CBP4 in aqueous phosphate buffer solution at pH 7.4 at 298 K. The excitation wavelength is at 352.0 nm. Inset: the nonlinear least-squares analysis to calculate the association constant using the fluorescence emission at 530 nm. Visible emission observed from samples of P and B in the

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• ][30]. They are characterized by narrow absorption and fluorescence emission bands with small Stokes shifts, high molar absorption coefficients, and high quantum yields. Their excitation and emission maxima are in the visible region, usually above 470 nm, and they show high thermal and photochemical

• ) demonstrating the sensing principle based on the pKa of the dye and the complex in the presence and absence of analyte. c) Structures of CB7 and BODIPY derivatives. a) Normalized absorption (solid line) and normalized fluorescence emission spectrum (dotted line) of 0.72 µM 1 in 30% (v/v) ACN in water, pH 7.0

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• tripyrrin moiety are 13.7(1)° and 18.4(1)°, respectively. The difference between the two dihedral angles is much larger than that in 3. The UV–vis/NIR absorption spectra of 3 and 3Pd are shown in Figure 5. However, no fluorescence emission can be observed for 3 and 3Pd. Both 3 and 3Pd display broad Soret

Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives

• Feng-Ming Xie,
• Qingdong Ou,
• Qiang Zhang,
• Jiang-Kun Zhang,
• Guo-Liang Dai,
• Xin Zhao and
• Huai-Xin Wei

Beilstein J. Org. Chem. 2018, 14, 869–874, doi:10.3762/bjoc.14.73

• . Moreover, their fluorescence emission peaks are in the blue fluorescence region at 408 nm and the fluorescence quantum efficiency (Φ) of CEPDO and CBPDO were 62.5% and 59.7%, respectively. Both CEPDO and CBPDO showed very high thermal stability with decomposition temperatures (Td) of 409 and 396 °C as well

• Table 1. Conclusion In summary, we have designed and synthesized two bipolar host materials CEPDO and CBPDO. CEPDO and CBPDO not only have a high triplet energy but also show a bipolar behavior. Moreover, their fluorescence emission peaks are blue fluorescence at 408 nm and the fluorescence quantum

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• uracil acted rather like a general fluorescence label. On the other hand, the fluorescent nucleobase 5-(pyren-1-yl)uracil in acpcPNA formed a specific Watson–Crick type base pairing with dA in the DNA strand, and the duplex formation was accompanied by a strong (up to 42-fold) fluorescence emission

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• last decades, complementary methods to ECD also were developed, for instance, vibrational CD (VCD) was successfully applied to investigate DNA/ligand interactions [11]. Furthermore, fluorescence detected circular dichroism (FDCD) combines the advantages of both CD and fluorescence emission technique

Development of a fluorogenic small substrate for dipeptidyl peptidase-4

• Futa Ogawa,
• Masanori Takeda,
• Kanae Miyanaga,
• Keita Tani,
• Ryuji Yamazawa,
• Kiyoshi Ito,
• Atsushi Tarui,
• Kazuyuki Sato and
• Masaaki Omote

Beilstein J. Org. Chem. 2017, 13, 2690–2697, doi:10.3762/bjoc.13.267

• quantum yield to 0.03. In spectroscopic terms, the fluorescence emission peaks of these compounds red-shifted with increasing TFPE substitution. Additionally, a large Stokes shift was observed for 1, which is important in view of the biomedical use of fluorescent compounds. Next, we changed the solvent

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• nucleoli. Noticeably, this pattern was not observed when the cells were labeled with 4. On the other hand fluorescence emission spectra of both compounds in cells were similar (Figure S7, Supporting Information File 1) and compatible with their counterparts registered in dichloromethane solution. This

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• = 75%) was high, comparable to that of phosphole and indole-fused pentacyclic heteroacene (Ф = 70%) [35]. On the other hand, a low fluorescence intensity was observed for phosphine sulfide 5 and selenide 6 (Ф = 1% and 0.3%, respectively). Quenching of fluorescence emission due to a soft sulfur

• phospholium salt, and the borane complex showed a high fluorescence emission. Further investigations are underway to develop functional materials including electronic devices and evaluate the physicochemical properties of these compounds by synthetic, theoretical, and spectroscopic studies. Phosphole-based

• tetracyclic heteroacenes. ORTEP drawing of compound 3 (left) and 4 (right) with 50% probability. All hydrogen atoms are omitted for clarity. One of two geometries in the unit cell was drawn for 4. UV–vis absorption (left) and normalized fluorescence emission (right, excitation at 335 nm) spectra in CH2Cl2

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

• derivatization of mycolactone A/B (1a,b) with a 2-naphthylboronate-based fluorogenic chemosensor (Figure 4). The latter complexes the 1,3-diol moiety proximal to the pentaene motif of the lower side chain, thus resulting in enhanced fluorescence emission intensity of the mycolactone band upon irradiation with

BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide

• Ludmila Škorpilová,
• Silvie Rimpelová,
• Michal Jurášek,
• Miloš Buděšínský,
• Jana Lokajová,
• Roman Effenberg,
• Petr Slepička,
• Tomáš Ruml,
• Eva Kmoníčková,
• Pavel B. Drašar and
• Zdeněk Wimmer

Beilstein J. Org. Chem. 2017, 13, 1316–1324, doi:10.3762/bjoc.13.128

• -terminated intermediate 5 in excellent yield (92%). Finally, CuAAC cycloadition of 5 and Tb-N3VA [31] gave the target fluorescent construct 6 in good yield (84%). The absorbance and fluorescence emission spectra of compounds 3–6 are depicted in Figure 2. Compounds 3–6 showed absorption and emission maxima at

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• autoclave chamber with heating to 200 °C for 12 h (Scheme 3) [29]. The fluorescence emission could be tuned by changing the ratio of sugar and KH2PO4. For instance a molar ratio of 1:26 (glucose/KH2PO4) afforded blue-fluorescent CDs (QY = 0.02), whereas a 1:36 ratio yielded green-fluorescent CDs (QY = 0.01

• crystallinity with blue-green emission. Most reported CD syntheses, regardless of the type of starting material or synthetic method, tend to produce CDs with blue-green fluorescence emission. Jana et al. reported a carbohydrate-based preparation to access yellow and red emissive CDs, demonstrating that fine

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• spectroscopic investigations on the conjugates were carried out in aqueous solutions. Figure 6 shows the absorption and fluorescence emission spectra of eosin Y conjugate 2–β-CD and, for comparison, of the free dye 2. Apart from a slight red shift of the absorption maximum, the absorption spectral profile in

• the visible region of the conjugate is similar to that of the free dye, ruling out any relevant aggregation phenomena. This hypothesis was well confirmed by the fluorescence emission spectrum, which exhibits an intense band maximum at 550 nm. The fluorescence quantum yield was Φf = 0.20, which is very

• corresponding 4–β-CD conjugate did not show either detectable fluorescence emission or 1O2 photogeneration. This is not surprising in light of the observed massive aggregation of this derivative in aqueous medium (see Figure 5). Studies currently in progress are addressed to better clarify this point and to

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

• Lukas J. Patalag and
• Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

• C27H38N2O2SNa+, 477.25462; found, 477.25542. Examples for previously prepared fluorescent fatty acids and our present work. Absorption spectra of fatty acids 3, 7 and 11. Solid lines show the UV absorption while dashed lines show fluorescence emission. Excitation was performed at the longest wavelength in each

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• constant of AdSq with the cyclodextrins in the CDV could be obtained by plotting the maximum fluorescence emission (at 676 nm) against the concentration of available cyclodextrin (Figure 3, bottom). The resulting Langmuir isotherm was fitted by linear regression (see Supporting Information File 1 for

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• evident that subtle changes in molecular orientation and packing, with a tendency to H-aggregate formation, are present, however, further work is being undertaken to better understand the underlying processes leading to these changes. Fluorescence emission spectra were collected using the same films as

• temperatures (Figure 10) but there is no appearance of the new shoulder, however as the films are rapidly cooled there may be a kinetic effect (see below). Variable temperature fluorescence emission spectra were recorded on BTR and BQR (Figure 9) using a similar setup as for the UV–vis measurements (Figure 8

• remain unclear and are the subject of further structural studies on BTR and BQR thin films. The appearance of the second fluorescence emission peak in variable temperature spectra on the POM stage, again not seen on the thin films (Figure 7c), has been examined in more detail. The thin films used to

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• CARY100 UV–visible spectrophotometer using the Cary WinUV Scan software 3.00(182). Fluorescence emission spectroscopy was conducted using a Perkin Elmer LS 55 fluorescence spectrometer. All in situ FTIR spectroscopy experiments (ReactIR, Mettler Toledo) were carried out using a ReactIR 15 with MCT

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• origin of the fluorescence emission will be also described by time-dependent density functional theory (TDDFT) calculations. The ability of the terpyridine compounds to bind poisoning metal cations was investigated by spectrophotometric titrations of methanolic 4′-azulenyl-substituted terpyridine

• spectroscopy in dichloromethane solution. The 2,2′:6′,2″-terpyridine moiety is an excellent chromophore with an absorption maximum at 279 in dichloromethane solution [8]. Upon 4′-substitution with a phenyl group the longest-wavelength absorption is not affected, only the fluorescence emission is shifted

• absorption maximum. Both compounds showed fluorescent emission upon excitation at wavelengths corresponding to their absorption maximum. The fluorescence spectra are shown in Figure 5. In the case of 4a, by excitation with 375 nm, a dual fluorescence emission is observed at 435 nm and 530 nm, respectively

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• indicates that the L binds copper as Cu2+. Fluorescence titrations of L with metal ions Fluorescence spectroscopy was applied to investigate the recognition properties of chemosensor L toward various metal ions in MeCN. In the absence of metal ions, the receptor L represents fluorescence emission at ≈365 nm

• +, Co2+, Ni2+, Cd2+, Ag+, Ba2+, K+, Na+ and Li+. The fluorescence spectra showed almost no obvious change relative to the free ligand L (Figure 4). Titration of L with Cu2+ resulted in a gradual quenching of the fluorescence emission at the 365 nm band as a function of increasing Cu2+ concentration. The

• the competitive recognition of Cu2+ by sensor L, the effect of Cu2+ was studied in the presence of other metal ions. The results showed that the fluorescence emission intensity of [L + Mn+] is altered in the presence of Cu2+ ions (Figure 6). It is noteworthy that complex [L + Mn+] exhibited no

Application of Cu(I)-catalyzed azide–alkyne cycloaddition for the design and synthesis of sequence specific probes targeting double-stranded DNA

• Svetlana V. Vasilyeva,
• Vyacheslav V. Filichev and
• Alexandre S. Boutorine

Beilstein J. Org. Chem. 2016, 12, 1348–1360, doi:10.3762/bjoc.12.128

• interaction of the F1-NH2-TO probe with the target duplex. To test the specificity of these probes we titrated them with a non-target duplex that resulted in a 1.5 times increase in fluorescence emission for the MM14 probe and also 8 times increase for the F1-NH2-TO probe (Figure 8). The non-specific increase

• absorption spectra in the interval 300–700 nm do not change upon DNA titration (data not shown), which means that increase in fluorescence emission is due to the increase of the quantum yield of fluorescence. Studies of interaction of the probes with fixed and live mouse cells are under investigation in the

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• preliminary form [9], fluorescence emission of their azomethine precursors was reported for pyrene-1-carboxaldehyde thiosemicarbazone and Schiff bases as well as their metal complexes [16][17][18][19][20][21]. Such properties were described for, e.g., ruthenium(II) complexes of (5-chloropyridin-2-yl)-(pyren-1

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• ] + [R] = 5.0 × 10−6 mol dm−3; λem at 358 nm. Reproduced with permission from [61]. Copyright 2004 John Wiley and Sons. Chiral discriminating sensor (relative stereochemistry shown) constructed using a good fluorophore (anthracene). Fluorescence emission intensity-pH profile of: (a) Sensor 15: 1.0 × 10−6

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• isolated in 87% yield. Photophysical properties of 3a–d and 4 As expected, thioamides 2a–d were nonfluorescent (thioamide group is a well-known fluorescence quencher [31]). In contrast, the corresponding amides 3a–d showed strong fluorescence emission in solution and in the solid state. We studied the

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• ); selected bond angles (o) N(1)–C(8)–O(1) 114.99(9), O(1)–C(8)–C(2) 119.76(8), N(1)–C(8)–C(2) 125.24(9), C(3)–C(2)–C(8) 117.85(8), C(1)–C(2)–C(8) 122.45(9). Electronic absorption (1, 2), fluorescence emission (λexc = 350 nm) (3, 4) and fluorescence excitation [λobs = 495 nm (5), λobs = 510 nm (6)] spectra of