  Interplay between structure and function in atomically thin crystalline
nanoribbons is sensitive to their conformations yet the ability to prescribe
them is a formidable challenge. Here, we report a novel paradigm for controlled
nucleation and growth of scrolled and folded shapes in finite-length
nanoribbons. All-atom computations on graphene nanoribbons (GNRs) and
experiments on macroscale magnetic thin films reveal that decreasing the end
distance of torsionally constrained ribbons below their contour length leads to
formation of these shapes. The energy partitioning between twisted and bent
shapes is modified in favor of these densely packed soft conformations due to
the non-local van Der Waals interactions in these 2D crystals; they subvert the
formation of supercoils that are seen in their natural counterparts such as DNA
and filamentous proteins. The conformational phase diagram is in excellent
agreement with theoretical predictions. The facile route can be readily
extended for tailoring the soft conformations of crystalline nanoscale ribbons,
and more general self-interacting filaments
