It shall be unlawful for any such officer, board, body or person to expend for the erection, improvement or repair of any building or structure, or for the purchase of any real estate or other property, or upon any contract or undertaking whatsoever to be performed in whole or in part by the state, any sum exceeding that which shall have been appropriated or authorized therefor by the Legislature, nor shall they incur any debt or obligation on any such account not expressly authorized by the Legislature, nor use in part payment only upon the purchase or construction of any land or structure any sum which shall have been appropriated or authorized by the Legislature in full payment for such object.