- A novel strategy for the design of smart supramolecular gels: Controlling stimuli-response properties through competitive coordination of two different metal ions
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By rationally introducing Ca2+ and Fe3+ into a supramolecular gel, a bimetal-gel CaFeG was prepared. CaFeG could reversibly "turn-on" its fluorescence upon sensing H2PO 4- with specific selectivity un
- Lin, Qi,Sun, Bin,Yang, Qing-Ping,Fu, Yong-Peng,Zhu, Xin,Zhang, You-Ming,Wei, Tai-Bao
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- A sensitive and selective sensor for picric acid detection with a fluorescence switching response
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A low molecular weight organogelator containing 3,5-substituted-1,3,4-oxadiazole and tetrazole units was synthesized and characterized. This compound is only soluble in DMSO and forms a stable gel. The solution and gel exhibit a blue light emission. The gel was characterized by atomic force microscopy, field-emission scanning electron microscopy, 1H NMR and fluorescence measurements. The gel to solution interconversion was reversible for many cycles of heating and cooling. The compound in solution exhibited a high selectivity for the detection of picric acid, a common explosive and water pollutant. Fluorimetric titration studies with nitro explosive compounds revealed that the emission of the compound was red shifted in response to the addition of picric acid, and exhibited a shifting of fluorescence from blue to green. Theoretical and experimental studies revealed that the sensing is due to the complexation of the picrate anion with the protonated fluorophore. The shifting of emission in response to picric acid in the visible region is ideal for the naked eye detection of explosives and therefore it is promising in comparison to the detection methods based on fluorescence quenching.
- Nath, Subrata,Pathak, Suraj Kumar,Pradhan, Balaram,Gupta, Ravindra Kumar,Reddy, K. Anki,Krishnamoorthy,Achalkumar, Ammathnadu S.
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- Double metal ions competitively control the guest-sensing process: A facile approach to stimuli-responsive supramolecular gels
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A facile approach to the design of stimuli-responsive supramolecular gels (SRSGs) termed double-metal-ion competitive coordination control is reported. By this means, the fluorescence signals and guest-selective responsiveness of the SRSGs are controlled
- Lin, Qi,Sun, Bin,Yang, Qing-Ping,Fu, Yong-Peng,Zhu, Xin,Wei, Tai-Bao,Zhang, You-Ming
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- A novel highly selective "turn-on" fluorescence sensor for silver ions based on Schiff base
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A novel optical chemical sensor L was designed and synthesized for the determination of silver ions. The sensor L was derived from 1-naphthaldehyde and 3,4,5-tris(hexadecyloxy)benzohydrazide. The sensor L shows high sensitivity and selectivity for Ag+ det
- Lin, Qi,Yang, Qingping,Sun, Bin,Wei, Taibao,Zhang, Youming
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- An efficient iodide ion chemosensor and a rewritable dual-channel security display material based on an ion responsive supramolecular gel
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By introducing multi-self-assembly driving forces, coordination binding sites and signal groups into the same molecule, a well designed functional gelator G1 was synthesized. The gelator G1 could form a stable Pb2+-coordinated supramolecular me
- Lin, Qi,Liu, Lu,Liu, Juan,Zheng, Feng,Zhang, You-Ming,Yao, Hong,Wei, Tai-Bao
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- Exceptional dual fluorescent, excited-state intramolecular proton-transfer (ESIPT) columnar liquid crystals characterized by J-stacking and large Stokes shifts
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Excited-State Intramolecular Proton-Transfer (ESIPT) fluorophores are emerging as promising future materials for electronic and biotechnological applications. ESIPT columnar (Col) liquid crystals (LCs) have been especially projected as the apt materials for advanced technological endeavors. But, there are hardly any explorations in this direction and thus, needing immediate attention. Herein we report on the synthesis, characterization, and ESIPT activity of a homologous series of novel phasmidic bis(N-salicylideneaniline) Col LCs. Optical microscopic, calorimetric and powder X-ray diffraction (XRD) studies evidence the occurrence of hexagonal columnar (Colh) phase having p6mm symmetry where the constituent slices result from the self-assembly of a pair of mesogens in a side-by-side manner facilitated by intense longitudinal π-π interactions. X-ray data confirm the absence of both directionally correlated tilting of the slices and transverse core-core interactions within the columns. Fluorescence probing clearly evidence the ESIPT occurring not only in DCM solution of the mesogens but also in their three-condensed states viz., solid, liquid crystal, and isotropic liquid phase; in general, two archetypal emission bands at ~430 nm (weak) and ~ 630 nm (strong) with large Stokes shifts (250–275 nm) of ESIPT phenomenon have been observed. The slow shift of emission maxima of the ESIPT fluorescence as a function of decreasing temperature without photoluminescence quenching coupled with the estimated tilt angle (?) of the slices normal to the columnar axis (37 to 42o), from the XRD data, confirm the formation of so-called Scheibe or J-aggregates. The redox activity, metal ion sensing ability, and solvatochromism of the mesogens have also been investigated. The study suggests that these ESIPT Col LCs with band-gap of about 3 eV can be regarded as wide-bandgap semiconducting materials having the electronic characteristics falling between those of conventional semiconductors and insulators.
- Kanakala, Madhu Babu,Yelamaggad, Channabasaveshwar V.
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- Columnar self-assembly of luminescent bent-shaped hexacatenars with a central pyridine core connected with substituted 1,3,4-oxadiazole and thiadiazoles
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Bent-shaped molecules with a central pyridine core flanked with substituted 1,3,4-oxadiazole and thiadiazole derivatives with a variation in the number and length of terminal tails were synthesized. Thiadiazole based compounds exhibited a wider mesophase
- Pradhan, Balaram,Gupta, Ravindra Kumar,Pathak, Suraj Kumar,De, Joydip,Pal, Santanu Kumar,Achalkumar, Ammathnadu S.
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p. 3781 - 3798
(2018/03/06)
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- Wide-Range Columnar and Lamellar Photoluminescent Liquid-Crystalline Lanthanide Complexes with Mesogenic 4-Pyridone Derivatives
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A series of liquid crystals with various lanthanide ions (EuIII, SmIII, and TbIII) was designed and prepared starting from the corresponding lanthanide nitrates and N-alkylated 4-pyridone derivatives bearing mesogenic 3,4,
- Chiriac, Laura F.,Pasuk, Iuliana,Secu, Mihail,Micutz, Marin,C?rcu, Viorel
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p. 13512 - 13522
(2018/09/06)
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- Multifunctional hexacatenar mesogen exhibiting supergelation, AIEE and its ability as a potential volatile acid sensor
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A bent shaped hexacatenar mesogen self-assembling into a columnar phase, in liquid crystalline and gel states exhibiting aggregation induced enhanced blue light emission has been synthesized. Its ability to detect volatile acids is demonstrated.
- Pradhan, Balaram,Gupta, Monika,Pal, Santanu Kumar,Achalkumar, Ammathnadu S.
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supporting information
p. 9669 - 9673
(2016/11/02)
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- Photoluminescent discotic liquid crystals derived from tris(N-salicylideneaniline) and stilbene conjugates: Structure-property correlations
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Luminescent discotic liquid crystals based on tris(N-salicylideneaniline)s [TSANs] bearing trans-stilbene fluorophores have been synthesized. Their mesomorphic and photophysical properties were studied. These TSANs existing in the form of C3h and Cs geometrical isomers of the keto-enamine tautomer self-assemble to form the columnar phase and exhibit fluorescence both in solution and mesophase states. These columnar mesophases also exhibit frozen (glassy) columnar phase, which ensures preserved fluorescence intensity, defect free alignment and simultaneous restriction on the motion of ionic impurities. These features make them promising candidates for the use in organic light emitting diodes, particularly as emissive layers. This study also led to an understanding about the dependence of their mesomorphism (mesophase type, stability and thermal range) and photophysical features on the number and pattern of their peripheral substitution, in comparison to the analogous columnar liquid crystalline TSANs reported earlier.
- Achalkumar, Ammathnadu S.,Veerabhadraswamy,Hiremath, Uma S.,Rao, Doddamane S. Shankar,Prasad, Subbarao Krishna,Yelamaggad, Channabasaveshwar V.
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p. 291 - 305
(2016/05/24)
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- Star-shaped fluorescent liquid crystals derived from s-triazine and 1,3,4-oxadiazole moieties
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Star-shaped molecules with a central triazine core appended with three 1,3,4-oxadiazole arms have been designed with the variation in the number, length and pattern of peripheral chain substitution. These compounds were investigated for their thermal, electrochemical and photophysical behavior. These nonconventional molecules stabilized wide range columnar phases and demonstrated how one can tune the liquid crystal self-assembly through simple structural modification. The photophysical properties of these star shaped molecules are extremely dependent on the number and pattern of peripheral chain substitution. These compounds exhibit blue and green luminescence in the solid/liquid crystal state. The ability to overcome aggregation induced quenching is due to the favorable packing of these molecules in the solid state. These solid-state emissive materials with good thermal stability and lower band gap may find applications in the construction of emissive displays and organic lasers.
- Pradhan, Balaram,Pathak, Suraj Kumar,Gupta, Ravindra Kumar,Gupta, Monika,Pal, Santanu Kumar,Achalkumar, Ammathnadu S.
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supporting information
p. 6117 - 6130
(2016/07/06)
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- Effect of Atomic-Scale Differences on the Self-Assembly of Thiophene-based Polycatenars in Liquid Crystalline and Organogel States
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Two series of polycatenars are reported that contain a central thiophene moiety connected to two substituted oxadiazole or thiadiazole units. The number, position, and length of the peripheral chains connected to these molecules were varied. The oxadiazol
- Pradhan, Balaram,Vaisakh,Nair, Geetha G.,Rao, D. S. Shankar,Prasad, S. Krishna,Sudhakar, Achalkumar Ammathnadu
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supporting information
p. 17843 - 17856
(2016/11/28)
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- s-Triazine-Based Functional Discotic Liquid Crystals: Synthesis, Mesomorphism and Photoluminescence
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A new series of C3-symmetric, π-conjugated molecules was designed, synthesized and characterized. The materials were derived from electron-accepting s-triazine, appended covalently to electron-donating styrylbenzene arms, and were readily prepared in excellent yield with high purity by means of three-fold condensation of triphosphonate with n-alkoxybenzaldehydes under Horner–Wadsworth–Emmons reaction conditions. Examination of the phase transitional properties by several complementary techniques evidenced self-assembly into a hexagonal columnar phase, occurring over wide and reasonable thermal ranges. The photophysical properties were studied both in solution and in the fluid/frozen columnar states by UV/Vis absorption and photoluminescence spectroscopy. The emission spectra obtained as a function of the temperature rule out the breaking-up of larger columns and a non-radiative, thermally activated process. A study carried out on thin films of the glassy columnar state, which accounts for conserved fluorescence, defect-free orientation, and freezing ionic species, with the help of atomic force microscopy (AFM) images, suggested a homogeneous granular morphology comprising fibrillar structures. Dissimilarities in the surface morphology and birefringence of thin films of the solid and frozen columnar states were clearly shown by Raman spectroscopy. An electrochemical investigation revealed a LUMO energy of ?4.0 eV. Thus, the discotic motifs presented herein meet certain criteria of organic materials, which are essential for developing electronic devices.
- Veerabhadraswamy, B. N.,Dambal, Hashambi K.,Rao, D. S. Shankar,Yelamaggad, C. V.
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p. 2225 - 2237
(2016/08/27)
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- Effect of regioisomerism on the self-assembly and photophysical behavior of 1,3,4-thiadiazole-based polycatenars
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A new class of polycatenars, where the central benzene ring is connected to two arms derived from substituted 1,3,4-thiadiazoles at the 1,3- and 1,4-positions, was synthesized and characterized. These thiadiazole-based molecules are promising as they stabilize columnar phases over a wide temperature range, in comparison to their oxadiazole analogues. The para-substituted polycatenars exhibited a columnar hexagonal and/or a columnar oblique phase, while the meta-substituted polycatenars exhibited solely a columnar oblique phase. The para-substituted polycatenars exhibited green emission, while the meta-substituted polycatenars exhibited blue emission in solution and film states. Stabilization of a broad range columnar phase and luminescence in the solid state make these new compounds promising from the viewpoint of applications in emissive displays. The self-assembly and luminescence of these regioisomers was greatly influenced by the molecular structure.
- Pathak, Suraj Kumar,Nath, Subrata,Gupta, Ravindra Kumar,Rao, D. S. Shankar,Prasad, S. Krishna,Achalkumar, Ammathnadu S.
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supporting information
p. 8166 - 8182
(2015/08/06)
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- Morphology tunable organogels based on dihydrazide derivatives
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We report on the organogels of a new series of compounds containing a dihydrazide unit in the rigid core and three long alkoxy chains. SEM images revealed that the morphologies of the xerogels strongly depend on the polarity of the gelling solvent. Textur
- Bai, Binglian,Wei, Jue,Zhao, Jian,Wang, Haitao,Li, Min
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scheme or table
p. 108 - 112
(2012/10/08)
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- Benzylidenehydrazine based room temperature columnar liquid crystals
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We report on the synthesis and investigation of self-assembly properties of new benzylidenehydrazine based compounds, namely N-(2,3,4- tridodecyloxybenzylidene)-3,4,5-N′-trialkoxybenzoylhydrazines. They were confirmed to exhibit wide ranges of room temper
- Shanker,Prehm,Yelamaggad,Tschierske
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supporting information; scheme or table
p. 5307 - 5311
(2011/12/15)
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- Columnar liquid-crystalline phase from a series of symmetrical bent diphenylamine derivatives: Synthesis and characterization
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A series of symmetrical bent-shaped materials with six alkoxy chains at the terminal position has been designed and synthesized. All except one exhibit columnar mesophase behavior. The mesomorphic properties of the compounds have been studied with the help of polaralizing optical microscopy (POM) and differential scanning colorimetry (DSC) experiments.
- Majumdar,Ansary, Inul,Roy
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scheme or table
p. 160 - 167
(2011/05/03)
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- Hydrazide-based organogels and liquid crystals with columnar order
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We report on the synthesis and self-assembly of a new series of compounds containing a hydrazide unit in the rigid core and three alkoxy chains with varying lengths. The compounds N-(3,4,5-cetyloxybenzoyl)-N′-(4′- nitrobenzoyl) hydrazine (C16) and N-(3,4,
- Bai, Binglian,Wang, Haitao,Xin, Hong,Zhang, Fenglong,Long, Beihong,Zhang, Xiaobing,Qu, Songnan,Li, Min
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p. 401 - 408
(2008/02/10)
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- Discotic bimetallomesogens: highly disordered mesophases of columnar hexagonal arrangements in bis(tetraketonate) vanadyl and copper complexes
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A series of bis(tetraketonate) complexes of dicopper and divanadyl has been prepared and their mesomorphic properties investigated by polarized optical microscopy and powder X-ray diffraction.
- Lai, Chung K.,Lin, Fun-Jane
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- 4,4'-Distyrylazobenzene as Mesogen
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From 3,4-dihydroxybenzaldehyde (1) the tetraalkoxy-substituted 4,4'-distyrylazobenzenes (E,E,E)-5a-c are synthesized.A similar reaction sequence leads from ethyl 3,4,5-trihydroxybenzoate (6) to the hexaalkoxy-substituted 4,4'-distyrylazobenzenes (E,E,E)-1
- Kosteyn, Frank,Zerban, Georg,Meier, Herbert
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p. 893 - 898
(2007/10/02)
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