Supramolecular encapsulation of benzimidazole-derived drugs by cucurbit[7]uril

2011 ◽  
Vol 89 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Apurba L. Koner ◽  
Indrajit Ghosh ◽  
Na'il Saleh ◽  
Werner M. Nau
Keyword(s):  
Photophysical Properties ◽  
Solubility Enhancement ◽  
Spectroscopic Techniques ◽  
Protonated Forms ◽  
The Absolute ◽  
Anthelmintic Drugs

UV–vis and NMR spectroscopic techniques were employed to demonstrate the ability of the synthetic macrocyclic host cucurbit[7]uril (CB7) to solubilize and stabilize widely used fungicides and anthelmintic drugs of the benzimidazole family in water, namely, albendazole (ABZ), carbendazim (CBZ), thiabendazole (TBZ), fuberidazole (FBZ), and the parent benzimidazole (BZ). CB7 binds the protonated forms of these guests very strongly (e.g., K = 2.6 × 107 L/mol for ABZ) but their neutral forms significantly more weakly (e.g., K = 6.5 × 104 L/mol for ABZ), which reflects a complexation-induced increase of their pKa values by 2.6 units for ABZ, 2.5 units for CBZ, 4.0 units for TBZ, 3.8 units for FBZ, and 3.5 units for BZ. The absolute drug solubilities increased upon complexation from 0.003 to 0.300 mmol/L for ABZ, from 0.160 to 1.12 mmol/L for CBZ, from 0.110 to 1.11 mmol/L for TBZ, and from 0.25 to 0.75 mmol/L for FBZ (for BZ, the solubility enhancement was found to be insignificant). Complexation by CB7 further improves the photostability of the drugs and alters their photophysical properties.

scholarly journals Probing the Interactions of Porphyrins with Macromolecules Using NMR Spectroscopy Techniques

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1942
Author(s):  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Nmr Spectroscopy ◽  
Photophysical Properties ◽  
Optical Methods ◽  
Spectroscopic Techniques ◽  
Control Mechanisms ◽  
Dynamic Information ◽  
Non Covalent Interactions ◽  
And Control ◽  
And Diffusion ◽  
Covalent Interactions

Porphyrinic compounds are widespread in nature and play key roles in biological processes such as oxygen transport in blood, enzymatic redox reactions or photosynthesis. In addition, both naturally derived as well as synthetic porphyrinic compounds are extensively explored for biomedical and technical applications such as photodynamic therapy (PDT) or photovoltaic systems, respectively. Their unique electronic structures and photophysical properties make this class of compounds so interesting for the multiple functions encountered. It is therefore not surprising that optical methods are typically the prevalent analytical tool applied in characterization and processes involving porphyrinic compounds. However, a wealth of complementary information can be obtained from NMR spectroscopic techniques. Based on the advantage of providing structural and dynamic information with atomic resolution simultaneously, NMR spectroscopy is a powerful method for studying molecular interactions between porphyrinic compounds and macromolecules. Such interactions are of special interest in medical applications of porphyrinic photosensitizers that are mostly combined with macromolecular carrier systems. The macromolecular surrounding typically stabilizes the encapsulated drug and may also modify its physical properties. Moreover, the interaction with macromolecular physiological components needs to be explored to understand and control mechanisms of action and therapeutic efficacy. This review focuses on such non-covalent interactions of porphyrinic drugs with synthetic polymers as well as with biomolecules such as phospholipids or proteins. A brief introduction into various NMR spectroscopic techniques is given including chemical shift perturbation methods, NOE enhancement spectroscopy, relaxation time measurements and diffusion-ordered spectroscopy. How these NMR tools are used to address porphyrin–macromolecule interactions with respect to their function in biomedical applications is the central point of the current review.

scholarly journals Photoinduced electron transfer processes of single-wall carbon nanotube (SWCNT)–based hybrids

Nanophotonics ◽  
2020 ◽  
Vol 9 (16) ◽  
pp. 4689-4701
Author(s):  
Lili Du ◽  
Wenjuan Xiong ◽  
Wai Kin Chan ◽  
David Lee Phillips
Keyword(s):  
Electron Transfer ◽  
Transient Absorption ◽  
Electronic Materials ◽  
Photophysical Properties ◽  
Functional Materials ◽  
Single Wall Carbon Nanotubes ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Single Wall Carbon ◽  
Electron Transfer Processes

AbstractIn this review, noncovalent functionalization of single-wall carbon nanotubes (SWCNTs) is briefly reviewed. The functional materials summarized here include metalloporphyrin derivatives, biomolecules and conjugated polymers. Notably, time-resolved spectroscopic techniques such as time-resolved fluorescence and transient absorption were employed to directly investigate the electron transfer and recombination processes between the functionalities and the SWCNTs. In addition, Raman spectroscopy is also useful to identify the interaction and the electron transfer direction between both the functionalities and the SWCNTs. An improved understanding of the mechanisms of these SWCNT-based nanohybrids in terms of their structural and photophysical properties can provide more insights into the design of new electronic materials.

scholarly journals Three New Cytotoxic Withanolides from the Chinese Folk Medicine Physalis angulata

2015 ◽  
Vol 10 (12) ◽  
pp. 1934578X1501001 ◽  
Author(s):  
Cai-Yun Gao ◽  
Ting Ma ◽  
Jun Luo ◽  
Ling-Yi Kong
Keyword(s):  
Cell Line ◽  
Folk Medicine ◽  
2D Nmr ◽  
Cytotoxic Activities ◽  
Spectroscopic Techniques ◽  
Aerial Parts ◽  
Physalis Angulata ◽  
The Absolute ◽  
New Compounds

Physagulides M-O, three new withanolides (1–3), were isolated from the aerial parts of Physalis angulata L. Their structures were elucidated through extensive spectroscopic techniques, including 1D and 2D NMR, and HRESIMS. The absolute configurations (22- R) of these new compounds were determined by CD analysis. Compounds 1 and 3 showed significant selective cytotoxic activities on the MG-63 cell line, with IC50 values of 4.28 and 5.44 μM, respectively.

Isolation, structure, and synthesis of chenopodanol and the absolute configuration of chenopodene and chenopodanol

1997 ◽  
Vol 75 (6) ◽  
pp. 634-640 ◽  
Author(s):  
Motoo Tori ◽  
Tomonobu Hamaguchi ◽  
Mamiko Aoki ◽  
Masakazu Sono ◽  
Yoshinori Asakawa
Keyword(s):  
Total Synthesis ◽  
Absolute Configuration ◽  
Active Form ◽  
Optically Active ◽  
Spectroscopic Techniques ◽  
The Absolute

(−)-Chenopodanol (2) has been isolated from the liverwort Marchantiachenopoda and its structure determined by spectroscopic techniques as well as by total synthesis. Chenopodene (1) has also been synthesized in an optically active form, resulting in revision of the originally assigned absolute configuration. Keywords: chenopodanol, chenopodene, liverwort, Marchantiachenopoda, sesquiterpene.

Synthesis and photophysical studies of non-covalently linked porphyrin dyads and triads

2007 ◽  
Vol 11 (02) ◽  
pp. 85-94 ◽  
Author(s):  
Punidha Sokkalingam ◽  
Sangita Santra ◽  
Ravikanth Mangalampalli
Keyword(s):  
Ring Current ◽  
Singlet State ◽  
Photophysical Properties ◽  
Spectroscopic Techniques ◽  
Current Effect ◽  
H Nmr ◽  
Nmr Study ◽  
Photophysical Studies ◽  
Ring Current Effect ◽  
Covalently Linked

Non-covalent porphyrin dyads and triads containing N 3 S porphyrin and RuN 4 porphyrin subunits were synthesized by treating meso-pyridyl-21-thiaporphyrin with RuTPP(CO)(EtOH) in toluene at refluxing temperature. The dyads and triads were characterized by various spectroscopic techniques and the properties were compared with the reported dyad containing N 4 and RuN 4 porphyrin subunits. The 1 H NMR study of dyads and triads indicated that the inner NH , β-heterocycle and meso-pyridyl protons of the 21-thiaporphyrin unit experienced large upfield shifts as compared to their corresponding monomeric meso-pyridyl-21-thiaporphyrins due to the ring current effect of RuTPP(CO) subunit. The singlet state photophysical properties of N 3 S porphyrin subunit in dyads and triads showed 50-80% quenching of fluorescence as observed previously for N 4- RuN 4 dyad due to heavy ruthenium ion(s).

scholarly journals Effect of Nickel Content on the Corrosion Resistance of Iron-Nickel Alloys in Concentrated Hydrochloric Acid Pickling Solutions

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Nabeel Alharthi ◽  
El-Sayed M. Sherif ◽  
Hany S. Abdo ◽  
S. Zein El Abedin
Keyword(s):  
Corrosion Resistance ◽  
Hydrochloric Acid ◽  
Electrochemical Impedance ◽  
Nickel Content ◽  
Spectroscopic Techniques ◽  
Current Time ◽  
Acid Pickling ◽  
Ni Content ◽  
Ni Alloy ◽  
The Absolute

The effect of Ni content on the resistance against corrosion of Fe-36% Ni and Fe-45% Ni alloys in 1 M hydrochloric acid pickling solution was reported. Various electrochemical and spectroscopic techniques such as potentiodynamic cyclic polarization (CPP), open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiostatic current-time (PCT), and scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) have been employed. CPP measurements indicated that the corrosion current and corrosion rate recorded lower values for the alloy that had higher nickel content. OCP curves proved that the presence of high Ni content shifts the absolute potential to the positive potential direction. EIS results revealed that the surface and polarization resistances were much higher for the alloy with higher Ni content. PCT curves also showed that the absolute currents were lower for Fe-45% Ni alloy. All results were in good agreement with others and confirmed clearly that the corrosion resistance in HCl solutions for Fe-45% Ni alloy was higher than that obtained for Fe-45% Ni alloy.

scholarly journals Struthiolanone: A Flavanone-Resveratrol Adduct from Struthiola Argentea

2008 ◽  
Vol 3 (2) ◽  
pp. 1934578X0800300
Author(s):  
Sloan Ayers ◽  
Deborah L. Zink ◽  
Robert Brand ◽  
Seef Pretorius ◽  
Dennis Stevenson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Absolute Configuration ◽  
High Resolution Mass Spectrometry ◽  
2D Nmr ◽  
Spectroscopic Techniques ◽  
Cd Spectrum ◽  
High Resolution Mass ◽  
The Absolute ◽  
Resolution Mass

Struthiolanone (1), a flavanone-resveratrol adduct, was isolated from Struthiola argentea. Its structure was determined by high-resolution mass spectrometry and 1D- and 2D-NMR spectroscopic techniques. The absolute configuration was determined by comparison of the CD spectrum of biflavonoids. This compound appears to be the first example of a flavanoid-stilbene adduct.

Spectroscopic and Photophysical Properties of Protonated Forms of Some Fluoroquinolones in Solutions

2011 ◽  
Vol 22 (1) ◽  
pp. 373-379 ◽  
Author(s):  
A. V. Polishchuk ◽  
E. T. Karaseva ◽  
T. B. Emelina ◽  
V. E. Karasev
Keyword(s):  
Photophysical Properties ◽  
Protonated Forms

Synthesis and photophysical properties of a new tetraphenylethylene-o-carborane-based star-shaped molecule

2021 ◽  
Author(s):  
Xiang Li ◽  
Qin Zhou ◽  
Miao Zhu ◽  
Wei Chen ◽  
Beibei Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Yield ◽  
Photophysical Properties ◽  
The Absolute

A novel TPE-o-carborane-based star-shaped molecule with a triphenylamine core was synthesized. In the solid state, the absolute luminescent quantum yield of this dendrimer can be improved to 62%.

scholarly journals Band Positioning in Boron Nitride and Metal-Free Photocatalysts via Photoelectron- and UV-Vis Diffuse Reflectance Spectroscopy

2020 ◽  
Author(s):  
Ravi Shankar ◽  
Anna Hankin ◽  
Gwilherm Kerherve ◽  
Camille Petit
Keyword(s):  
Boron Nitride ◽  
Band Structure ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Energy Scale ◽  
Amorphous Semiconductors ◽  
Spectroscopic Techniques ◽  
Absolute Energy ◽  
The Absolute

<p>New photocatalysts, particularly porous ones such as porous boron nitride, have emerged that exhibit complex structures and for which, there is limited knowledge of the electronic structure. Gaining insight into their complete band structure on the absolute energy scale will help assessing their suitability for a given photocatalytic reaction. To address this, we rationalise key concepts of band positioning alignment for both porous and non-porous semiconductors on the absolute energy scale. The approach employs a range of techniques generally accessible to many research groups. It involves a combination of spectroscopic techniques, namely X-ray photoelectron spectroscopy to determine the work function and valence band offset, and UV-Vis diffuse reflectance spectroscopy to measure the band gap. We apply this to present the complete band structure of boron nitride, in both porous and non-porous forms. We validate our methodology by comparing the experimentally obtained band structure for graphitic carbon nitride and amorphous boron, both amorphous semiconductors with a known band structure. We show how this can help predict possible photocatalytic reactions and demonstrate this in the context of CO2 photoreduction. With porous materials, such as porous BN, garnering increasing interest for photocatalytic applications, shedding light on their band structures could pave the way towards a methodical tuning and optimization of the photochemistry of these materials. </p>

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