“…According to the aforementioned criteria about hydrogen bonding, the BCP designated as 77 should not indicate that there is an intramolecular hydrogen bond in the title compound. Although the NBO analysis and QTAIM study have already been used as powerful tools to investigate intra- or intermolecular hydrogen bonding of several systems [ 54 , 59 , 60 , 61 , 62 , 63 ], they seemed not to be suitable to describe the intramolecular hydrogen bonds among the title compound in this study. Figure 10 The (3,-3), (3,-1), and (3,+1) BCPs of the title compound.…”
“…According to the aforementioned criteria about hydrogen bonding, the BCP designated as 77 should not indicate that there is an intramolecular hydrogen bond in the title compound. Although the NBO analysis and QTAIM study have already been used as powerful tools to investigate intra- or intermolecular hydrogen bonding of several systems [ 54 , 59 , 60 , 61 , 62 , 63 ], they seemed not to be suitable to describe the intramolecular hydrogen bonds among the title compound in this study. Figure 10 The (3,-3), (3,-1), and (3,+1) BCPs of the title compound.…”
“…Isoniazid 4 , an FDA-approved antibacterial prescription medicine for the prevention and treatment of tuberculosis, has a similar structure to 2 ; however, it showed no CEST contrast, and neither did nicotinic hydrazide 5 ( Figure S2c,d ). 2-picolinyl hydrazide 6 with its nitrogen on a pyridine ring available for hydrogen bonding with the amide group [ 43 ], displayed a CEST contrast of 5.0 ppm downfield from water ( Figure 1 b). Picolinamide 7 also shows CEST signal at 4.4 ppm ( Figure S2e ).…”
Chemical exchange saturation transfer (CEST) MRI is a versatile molecular imaging approach that holds great promise for clinical translation. A number of compounds have been identified as suitable for performing CEST MRI, including paramagnetic CEST (paraCEST) agents and diamagnetic CEST (diaCEST) agents. DiaCEST agents are very attractive because of their excellent biocompatibility and potential for biodegradation, such as glucose, glycogen, glutamate, creatine, nucleic acids, et al. However, the sensitivity of most diaCEST agents is limited because of small chemical shifts (1.0–4.0 ppm) from water. To expand the catalog of diaCEST agents with larger chemical shifts, herein, we have systematically investigated the CEST properties of acyl hydrazides with different substitutions, including aromatic and aliphatic substituents. We have tuned the labile proton chemical shifts from 2.8–5.0 ppm from water while exchange rates varied from ~680 to 2340 s−1 at pH 7.2, which allows strong CEST contrast on scanners down to B0 = 3 T. One acyl hydrazide, adipic acid dihydrazide (ADH), was tested on a mouse model of breast cancer and showed nice contrast in the tumor region. We also prepared a derivative, acyl hydrazone, which showed the furthest shifted labile proton (6.4 ppm from water) and excellent contrast properties. Overall, our study expands the catalog of diaCEST agents and their application in cancer diagnosis.
“…tems. [49][50][51][52][53][54][55][56] According to QTAIM, if D-H forms a hydrogen bond with A, there should be a CP between H and A. In addition, criteria about the electron density (ρ b ) and the Laplacian of electron density (∇ 2 ρ b ) at BCPs have been established by Koch and Popelier to distinguish hydrogen bonding from van der Waals interactions.…”
The anilide compound named (Z)-4-(2-methoxy-4-nitrophenyl)amino)-4-oxobut-2-enoic acid (MAOA) has been synthesized by the chemical reaction of 2-methoxy-4-nitroaniline and maleic anhydride in ethyl acetate. The synthesized compound was characterized by elemental analysis, FT-IR and UV-Vis spectroscopy, and TGA/DSC technique. Furthermore, the crystal structure was analyzed by the single crystal X-ray diffraction (SC XRD) technique. The supramolecular assembly of MAOA in terms of non-covalent interactions was explored by Hirshfeld surface analysis. Void analysis inferred that MAOA is expected to have good mechanical properties. The crystal packing environment was further investigated by interaction energy between molecular pairs and energy frameworks. Moreover, the result of the gas-phase DFT study showed that there is an intramolecular N–H···O and O–H···O hydrogen bond in MAOA due to the distance between D and A being smaller than the sum of their van der Waals radii. The result of the QTAIM study showed that there should also be an intramolecular CH···O hydrogen bond with a strength of 3.40 kcal/mol in MAOA.
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