Two dimensional structures like graphene nanostructures exhibit vanous phys icalrnproperties on in-plane anchoring of fun ctional groups. We have investi gated thernelectronic band structure, the density of states (DOS), and the current-voltage (I-V)rncharacteri stics of pri stine and armchair nanoribbons (AGNRs) functionali zed withrnaromatic ring (C6) by first- princi ples calculations with the help of ab-initio DFT code. ArnC6 ring structure is in-plane anchored to the nano-ribbon to maximize the effects ofrnfunctionali zation on the properties of the nanostructures of various widths. Samples arerntheoretically modeled, both in the periodic and open system nano-device configurations,rnby using arm-chair nanoribbons of different widths with and without ring attachments.rnSubsequently, the as-prepared nano-devices are simulated and their I-V characteri sticsrnare studied. The resul ts of these simulations are analysed by using the charge transfer,rnwhich takes place during the final self consistent calculation routines amongst the C-ringrnand its ribbons. We found a significant amount of change in the electro nic density ofrnstates of the semiconducting ribbons due to the presence of C6-rings. Also, we haverndemonstrated that the C-ring attachment can be effective ly used to tailor the energyrnbandgaps of the semiconducting ribbons. In addition to this we have also showed thernnano-device feasibility of such ring functionalized ribbons. The property of bandgaprndependence on aromatic ring is also studied. Finally the prospects of functionalizedrnnanostruclllres of graphene are also discussed in this thesis, especially, the electronic andrntransport properties of armchair ribbons are di scussed with respect to ringrnfunctionalizations.