Hyperfine Interactions in the NV-13C Quantum Registers in Diamond Grown from the Azaadamantane Seed

Nanostructured diamonds hosting optically active paramagnetic color centers (NV, SiV, GeV, etc.) and hyperfine-coupled with them quantum memory 13C nuclear spins situated in diamond lattice are currently of great interest to implement emerging quantum technologies (quantum information processing, quantum sensing and metrology). Current methods of creation such as electronic-nuclear spin systems are inherently probabilistic with respect to mutual location of color center electronic spin and 13C nuclear spins. A new bottom-up approach to fabricate such systems is to synthesize first chemically appropriate diamond-like organic molecules containing desired isotopic constituents in definite positions and then use them as a seed for diamond growth to produce macroscopic diamonds, subsequently creating vacancy-related color centers in them. In particular, diamonds incorporating coupled NV-13C spin systems (quantum registers) with specific mutual arrangements of NV and 13C can be obtained from anisotopic azaadamantane molecule. Here we predict the characteristics of hyperfine interactions (hfi) for the NV-13C systems in diamonds grown from various isotopically substituted azaadamantane molecules differing in 13C position in the seed, as well as the orientation of the NV center in the post-obtained diamond. We used the spatial and hfi data simulated earlier for the H-terminated cluster C510[NV]-H252. The data obtained can be used to identify (and correlate with the seed used) the specific NV-13C spin system by measuring, e.g., the hfi-induced splitting of the mS = ±1 sublevels of the NV center in optically detected magnetic resonance (ODMR) spectra being characteristic for various NV-13C systems.

Bulk polarity of 3,5,7-trinitro-1-azaadamantane mediated by asymmetric NO2(lone pair)...NO2(π-hole) supramolecular bonding

Molecular crystals exhibiting polar symmetry are important paradigms for developing new electrooptical materials. Though accessing bulk polarity still presents a significant challenge, in some cases it may be rationalized as being associated with the specific molecular shapes and symmetries and subtle features of supramolecular interactions. In the crystal structure of 3,5,7-trinitro-1-azaadamantane, C₉H₁₂N₄O₆, the polar symmetry of the molecular arrangement is a result of complementary prerequisites, namely the C_3v symmetry of the molecules is suited to the generation of polar stacks and the inherent asymmetry of the principal supramolecular bonding, as is provided by NO₂(lone pair)...NO₂(π-hole) interactions. These bonds arrange the molecules into a trigonal network. In spite of the apparent simplicity, the structure comprises three unique molecules (Z' = 1/3 + 1/3 + 1/3), two of which are donors and acceptors of three N...O interactions and the third being primarily important for weak C-H...O hydrogen bonding. These distinct structural roles agree with the results of Hirshfeld surface analysis. A set of weak C-H...O and C-H...N hydrogen bonds yields three kinds of stacks. The orientation of the stacks is identical and therefore the polarity of each molecule contributes additively to the net dipole moment of the crystal. This suggests a special potential of asymmetric NO₂(lone pair)...NO₂(π-hole) interactions for the supramolecular synthesis of acentric materials.

Mechanochemical synthesis and X-ray structural characterization of three 3-nitrophenol cocrystals with three aminal cage azaadamantanes: the role of the stereoelectronic effect on intermolecular hydrogen-bonding patterns

The structures of the cocrystalline adducts of 3-nitrophenol (3-NP) with 1,3,5,7-tetraazatricyclo[3.3.1.1^3,7]decane [HMTA, (1)] as the 2:1:1 hydrate, 2C₆H₅NO₃·C₆H₁₂N₄·H₂O, (1a), with 1,3,6,8-tetraazatricyclo[4.3.1.1^3,8]undecane [TATU (2)] as the 2:1 cocrystal, 2C₆H₅NO₃·C₇H₁₄N₄, (2a), and with 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane [TATD, (3)] as the 2:1 cocrystal, 2C₆H₅NO₃·C₈H₁₆N₄, (3a), are reported. In the binary crystals (2a) and (3a), the 3-nitrophenol molecules are linked via O-H...N hydrogen bonds into aminal cage azaadamantanes. In (1a), the structure is stabilized by O-H...N and O-H...O hydrogen bonds, and generates ternary cocrystals. There are C-H...O hydrogen bonds present in all three cocrystals, and in (1a), there are also C-H...O and C-H...π interactions present. The presence of an ethylene bridge in the structures of (2) and (3) defines the formation of a hydrogen-bonded motif in the supramolecular architectures of (2a) and (3a). The differences in the C-N bond lengths of the aminal cage structures, as a result of hyperconjugative interactions and electron delocalization, were analysed. These three cocrystals were obtained by the solvent-free assisted grinding method. Crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation from a mixture of hexanes.

Synthesis and Analgesic Activity of Amines Combining Diazaadamantane and Monoterpene Fragments

BACKGROUND

It was found earlier that compounds combining diazaadamantane and monoterpene moieties possessed promising analgesic activity along with low acute toxicity and the lack of ulcerogenic activity.

OBJECTIVE

In this paper, new structural analogues of the most active compounds were synthesized and evaluated for their analgesic activity.

METHODS

Their structures were confirmed by various analytical methods, such as 1H and 13C NMR, HRMS. All of them were evaluated for analgesic activity at a dose of 20 mg/kg or less using acetic acid-induced writhing test and hot plate test.

RESULTS

Some compounds showed analgesic activity in acetic acid-induced writhing test. One of the synthesized compounds demonstrated high analgesic activity in both tests with 46% effect in acetic acid-induced writhing test and 89% effect in hot plate test. Both structural fragments of this compound did not possess any analgesic effect at a dose of 20 mg/kg.

CONCLUSION

Structure-activity relationships indicated that the most active compound combines fragments of (-)-myrtenal and 6-amino-5,7-dimethyl-1,3-diazaadamantane. Both parts of the molecule are important for demonstrating analgesic activity.