Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• multiblock copolymers with the possibility to introduce stimuli-responsive functionalities were obtained using a bimetallic ruthenium initiator [74]. The initiator allowed for the single-step fabrication of symmetrically end-functionalized telechelic polymers using ROMP and functional chain terminators

Lectins of Mycobacterium tuberculosis – rarely studied proteins

• Katharina Kolbe,
• Sri Kumar Veleti,
• Norbert Reiling and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2019, 15, 1–15, doi:10.3762/bjoc.15.1

• successful strategies to survive, replicate and persist within macrophages for days, months or even years, including highly-specialized metabolic pathways for nutrient acquisition and stress-responsive processes for protection against the immune system [7][8][9][10][11][12]. In this regard, invasion of

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• topologically complex TTF catenanes and cage compounds [52][74][102][103][104]. 6.1. Stimuli-responsive circumrotation The TTF-based catenane 26 allows implementing a stimuli-responsive circumrotation motion (Figure 24) [105]. Similar to the corresponding donor–acceptor rotaxanes, the macrocycle preferentially

• organosulfur compound TTF developed from a molecular switch with multiple electronic and material applications to one of the most widely used building blocks for the construction of stimuli-responsive MIMs and functional molecular devices. The development of straightforward organic reactions to implement TTFs

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• and thiol functional groups. The reversible shuttling movement of the macrocycle between two different recognition sites on the molecular thread can be driven by external acid and base. This kind of rotaxane bearing functional groups provides a powerful platform for preparing stimuli-responsive

• ][5][6][7]. During the past years, a large number of different MIMs has been constructed, such as handcuff catenane [8], molecular elevators [9][10], molecular muscles [11][12], trefoil necklace [13][14][15], molecular walkers [16][17][18] and molecular pumps [19][20]. Combining the stimuli-responsive

• , which act as important precursors for constructing stimuli-responsive supramolecular materials [21][22]. Rotaxanes [23][24][25][26][27][28][29][30][31], as one of the most important MIMs, have been deeply investigated because of their excellent properties and convenient synthesis. By introducing various

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• gels are typically made of low-molecular-weight (LMW) compounds self-assembled in different solvents via non-covalent interactions. In most cases, this feature enables reversible stimuli-responsive gel-to-sol transitions [31]. Usually, the entanglement of 1D nanofibers of gelator molecules generates a

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• ; Introduction Thermo-responsive molecules exhibiting a lower critical solution temperature (LCST) are very important for applications such as controlled drug release [1], molecular separation [2], and tissue culture substrates [3]. Poly(N-isopropylacrylamide) (pNIPAAm) is a widely used thermo-responsive polymer

• , which exhibits a clouding point around 32 °C [1][2][3][4]. Recently, thermo-responsive molecules with additional functions have been developed to replace pNIPAAm [5][6][7][8][9][10]. For example, we have developed thermo-responsive macrocyclic molecules which exhibit LCST behavior regulated by host

• -responsive LCST changes are very rare, while there have been some examples of LCST control using ionic chemical stimuli [5][6]. Results and Discussion Supramolecular structure and clouding point of bicyclic compound 3 The bicyclic compound 3 was prepared using a copper(I)-catalyzed alkyne–azide cycloaddition

Graphitic carbon nitride prepared from urea as a photocatalyst for visible-light carbon dioxide reduction with the aid of a mononuclear ruthenium(II) complex

• Kazuhiko Maeda,
• Daehyeon An,
• Ryo Kuriki,
• Daling Lu and
• Osamu Ishitani

Beilstein J. Org. Chem. 2018, 14, 1806–1812, doi:10.3762/bjoc.14.153

• -responsive photocatalyst mostly for H2 evolution from aqueous triethanolamine (TEOA) solution [2][3][5]. The present work also compares the activities for CO2 reduction with those for H2 evolution in order to obtain a better understanding on photocatalytic activities of g-C3N4 for different kinds of

Synthesis of diamido-bridged bis-pillar[5]arenes and tris-pillar[5]arenes for construction of unique [1]rotaxanes and bis-[1]rotaxanes

• Ying Han,
• Li-Ming Xu,
• Cui-Yun Nie,
• Shuo Jiang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2018, 14, 1660–1667, doi:10.3762/bjoc.14.142

• explosive development on the construction of various supramolecular devices and diverse responsive materials has been reported by using diverse functionalized pillararenes [33][34][35]. Due to easily preparation and suitable cavity, functionalized pillar[5]arenes were widely used as wheel component for

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• binding behavior of ZB4 and lays the basis for the construction of stimuli-responsive materials with ZB4 as a major component. Keywords: conformations; host–guest chemistry; macrocycles; supramolecular chemistry; zorb[4]arene; Introduction Macrocyclic receptors are the principal workhorses used in

• understand the importance of conformational adaptivity in biomolecular recognition and even design stimuli-responsive materials by harnessing this large amplitude of conformational changes. X-ray single crystal structure of ZB4 and the host–guest complexes. a) ZB4, b) 2+@ZB4-IV, c) 3+@ZB4-IV, d) 10+@ZB4-I

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• important classes of molecular switches is crucial for the design of light-responsive materials using this entity. Herein, we present the stabilization of metastable (Z)-azobenzenes by London dispersion interactions, even in the presence of comparably stronger hydrogen bonds in various solvents. The Z→E

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• different enzymes and/or the tumor microenvironment might trigger the improper release of the drug from the PDC, i.e., to end up with the drug-carrying part of the linker. Another class of linkers is the stimuli-responsive/degradable linkers, designed to achieve an efficient release of the drug from the

• enzyme-hydrolyzable units (EHU) responsive to proteases are degradable peptide linkers that have attracted significant interest due to the specificity of certain enzymes and there has been a dramatic escalation over in the past years. The most representative examples in this field are the MMP-2/9 (matrix

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• conversion of glucose in a tandem reaction [82]. The hydrophilic block of their polymersomes was PEG, and the hydrophobic block contained both poly[2-(diethylamino)ethyl methacrylate] (PDEAEM) which is pH responsive, and poly[4-(3,4-dimethylmaleimido)butyl methacrylate] (PDMIBM) as cross-linker. The activity

• -soluble polymers [109]. For instance, PNIPAM is a thermo-responsive polymer, which has a lower critical solution temperature (LCST) of 32 °C. Above the LCST, individual polymer chains switch from a swollen coil configuration to a collapsed globular one, providing a nano-environment that is suitable for

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• under different stimuli. The interest in stimuli-responsive ONs for gene silencing functions has been notable in recent years. The ON prodrug strategies usually help to overcome limitations of natural ONs due to their low metabolic stability and poor delivery. Nevertheless, compared to permanent ON

• the modification in the nucleotide: the internucleosidic phosphate, the nucleobase, the sugar or the extremities of ONs. Moreover, the review provides a current and detailed account of stimuli-responsive ONs with the main goal of gene silencing. However, for some stimuli-responsive ONs reported in

• this review, no application for controlling gene expression has been shown, but a certain potential in this field could be demonstrated. Additionally, other applications in different domains have been mentioned to extend the interest in such molecules. Keywords: enzymolabile group; light-responsive

Fluorogenic PNA probes

• Tirayut Vilaivan

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

• they will be non-responsive to the base pairing similar to PNA carrying tC or tCO [177]. Pyrrolocytosine is another intrinsically fluorescent hydrogen-bond-forming nucleobase that has been extensively studied in a DNA context [188][189]. When incorporated into PNA, the simple phenyl-substituted

• into PNA, these PhpC derivatives exhibited a bright blue fluorescence with large fluorescence quantum yield (0.5–0.6), which can be useful for monitoring the cellular uptake and distribution of PNA [192]. In addition, the fluorescence was responsive to the base pairing, where up to 60% quenching was

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

• Marco Russo,
• Daniele La Corte,
• Annalisa Pisciotta,
• Serena Riela,
• Rosa Alduina and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271

• ][41]. Moreover, the same products have been used for the synthesis of pH-responsive nanosponges [42]. In view of possible further applications, the present work is aimed at verifying the abilities of AmCD materials synthesized by us to act as bimodal supramolecular ligands. To the best of our

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• materials [90]. Such type of chelating agents was also designed to develop responsive contrast agents for magnetic resonance spectroscopy [91]. Acyclic diamine compounds (e.g., 15, Figure 4) possessing phosphonic acid groups as additional coordination sites or the tetraazamacrocyclic compound 14 were also

Theoretical simulation of the infrared signature of mechanically stressed polymer solids

• Matthew S. Sammon,
• Milan Ončák and
• Martin K. Beyer

Beilstein J. Org. Chem. 2017, 13, 1710–1716, doi:10.3762/bjoc.13.165

• in stress-induced aging of polymeric materials [1][10]. On the other hand, elegant routes have been established to harness this effect for the design of self-healing and stress-responsive materials [11][12][13][14][15]. The influence of an external force on the molecular structure of a polymer can be

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• spiropyran-modified agarose gel [14][15] and the creation of light-responsive nanopores through modification of natural channel proteins [16]. Furthermore, addition of an N-alkylcarboxylate moiety is a common tactic used to enhance water solubility of spiropyran derivatives [6]. Spiropyran–metal cation

Grip on complexity in chemical reaction networks

• Albert S. Y. Wong and
• Wilhelm T. S. Huck

Beilstein J. Org. Chem. 2017, 13, 1486–1497, doi:10.3762/bjoc.13.147

• of a bilayer network composed of the mechanical action of a temperature-responsive gel coupled with various exothermic reactions. Reprinted with permission from [34], copyright 2012 Nature Publishing Group. (b) Small dynamic combinatorial library made from dithiol building blocks. Adapted with

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• and friction by applying external stimuli onto the responsive ditopic linkers [47][48][49]. In contrast to previous work our molecular toolkit, based on ditopic connector molecules, allows the independent determination of unspecific interactions between CD polymers at tip and planar surface as well as

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

• CDs. Subsequently in 2014, the same group was able to show that coating of calcium alginate (CA) beads with chitosan hydrogel-based CDs yielded a new nanomaterial that could be employed as a pH-responsive drug-delivery vehicle (Scheme 21) [56]. The CDs were used as a protective layer onto the CA beads

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

• high purity through an improved synthetic route. The prepared CD conjugates have been thoroughly characterized by 1D and 2D NMR experiments. While the eosin B (4)-β-CD conjugate was not light responsive, probably due to self-aggregation phenomena, the eosin Y conjugate 2–β-CD showed excellent

A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation

• Wangkhem P. Singh and
• Rajkumar S. Singh

Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17

• such as acids or bases [17], metal ions [18], oxidation and reduction [19], reactive species enzymes, etc. Such responsive gel systems are highly desirable in stimuli-responsive sensor materials, drug delivery, catalysis, nano- and mesoscopic assemblies, light harvesting systems, and many others [20

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• thermo- [18] or/and pH [19] responsive polymers. Besides classical alkylation reactions, Reinecke et al. performed ring-opening reactions to insert functional groups and aromatic side chains [20][21]. Furthermore, they investigated the formation of homogeneous [22] and amphiphilic [23] N-VP networks

The role of alkyl substituents in deazaadenine-based diarylethene photoswitches

• Christopher Sarter,
• Michael Heimes and
• Andres Jäschke

Beilstein J. Org. Chem. 2016, 12, 1103–1110, doi:10.3762/bjoc.12.106

• DNA photoswitches for the application in bionanotechnology and synthetic biology. Keywords: diarylethene; nucleoside; electrocyclic rearrangement; photochromism; photoswitch; Introduction Most biomacromolecules are per se not responsive to light. Their conversion into photoresponsive molecules opens