Non-canonical nucleobase pairs are hydrogen bonded structures, wherein the hydrogen bonding differ from the patterns observed in Watson-Crick base pairs. Non-canonical DNA and RNA fragments are formed as a result of secondary structures and include G-quadruplexes, triplex forming oligos, hairpins, and i-Motif. The hydrogen bond interactions in free-standing non-canonical bases enables them to be adsorbed on surfaces and this has been exploited for various applications in nano mechanics. However, the detailed electronic and structural properties of these interactions are not fully known. Using Density Functional Theory, we perform gas and solvent phase studies on the structure and electronic properties of some of the adenine homodimers that has been crystalized and reported in the Cambridge Structural Database. The dispersion-corrected density functionals PBE-D2, wB97-xD, B97-D3, along with M06-2X, B3LYP, and MP2 were considered with 6-31G(d,p) basis set. In gas phase, the most stable adenine dimer has a binding energy of ~ -26.18 kcal/mol at PBE-D2/6-31G(d,p) level and is stabilized solely by N-H_N bonds (2.79 Å). The binding energy of adenine dimers decreases by ~ 10.2 kcal/mol for structures involving N-H_N and C-H_N bonds with subsequent increase in the average hydrogen-donor-acceptor distance. We compared the binding energy to G-G dimer = -34.13 kcal/mol at PBE-D2/6-31G(d,p) level, G-C dimer = -22.71 kcal/mol at B3LYP/6-311++G(d,p) level and -25.4 kcal/mol at MP2/6-31G** level and the experimental value of -21.0 and -12.4 kcal/mol for G-C and A-T pairs, respectively. The binding energy of adenine dimers in implicit solvent revealed screening of intermolecular hydrogen bonds with subsequent decrease in binding energy and increase in hydrogen bond distance compared to gas phase. We find N-H_N bond to be the most favorable hydrogen bond in stabilizing the non-canonical base pairs. The result from this study is expected to 1) predict the type and strength of hydrogen bonding in artificial base pairs, 2) establish a reliable understanding of the non-covalent interactions (hydrogen bonding and π–stacking) within adenine dimers, and 3) explore this knowledge for de novo design and applications in bio-sensing and DNA base self-assembly on the interface.